BASIC CHEMICAL DEFINITIONS
Chemists make a distinction between substances and mixtures.
Substance – pure, containing only one type of particle. A particle could be an element or a compound.
Element – one type of atom
Compound – one type of molecule or crystal
Mixture – contains 2 or more types of particles that have not been chemically combined
Mixtures fall into two categories based on the distribution of particles:
Hetero means
 Heterogeneous mixture- a mixture in which there is an uneven
distribution of materials
different.
o sand in water
o tossed salad
Homo means
o oil in water
same.
 Homogeneous mixture – a mixture in which all of the particles are evenly
distributed
o One example is salt water
o Homogeneous mixtures are commonly referred to as solutions. In a solution one type of
particle spreads out to fill the spaces between the particles of a second
substance.
o A homogeneous mixture has a solute and a solvent
Soluble means able
 Solute – substance that is being dissolved
to dissolve
 Solvent – substance that is used to dissolve a second
substance
Insoluble means not
 Most common solvents are water and alcohol.
able to dissolve
 In salt water salt is the solute and water is the solvent
Matter
Mixture
Substance
1 kind of particle
more than 1 kind
of particle
Element
Compound
Heterogeneous
Homogeneous
Oxygen (O2)
(Water H2O)
(Sand in water)
(Salt water)
HISTORY OF OUR UNDERSTANDING OF
ATOMIC STRUCTURE:
GREEK PHILOSOPHERS:
460 – 380 BC DEMOCRITUS:
He came to the conclusion that matter could not be divided up into smaller and smaller pieces forever.
Eventually the smallest possible piece would be obtained, he called this particle the atom. The word atom
comes from the Greek word atomos which means “not to be cut or indivisible”.
384 – 322 BC ARISTOTLE:
All things are made up of 4 elements, earth, air, fire and water. The
proportions of these elements present determines something’s properties.
The followers of Democritus, called the Atomists, debated Aristotle and lost
the debate resulting in the acceptance of Aristotle’s ideas for the next 2000
years.
DEVELOPMENT OF SCIENTIFIC CONCEPTS
1766 – 1844 JOHN DALTON:
Was an English chemist who based on experimentation and a review of the scientific findings of the time came
up with a new concept of the atom, based on 4 atomic laws:
1. All elements are composed of atoms. Atoms are indivisible and indestructible particles. (He gave credit
to Democritus for this idea.)
2. There are as many different kinds of atoms as there are elements. Atoms of the same element are
exactly alike. Atoms of different elements are different.
3. Compounds are formed by the joining of atoms of two or more elements. The smallest particle of a
compound is called a molecule.
4. Chemical changes involve whole atoms or groups of atoms, but never fractions of atoms.
Dalton’s model became the foundation of modern chemistry but eventually modifications were required.
1897 – JOSEPH J. THOMSON
The first to show atoms were made of smaller particles.
He was responsible for finding the electron (negative
charge).
He described the already known neutral atom to be a
pudding-like positively charged material throughout which
negatively charged electrons were scattered,
like plum-pudding with raisins.
1903 – ERNEST RUTHERFORD:
Ernest Rutherford, English physicist in 1908. While conducting an
experiment involving firing a stream of tiny positively charged
particles at a thin sheet of gold foil, he discovered most of his
positively charged “bullets” passed right through the gold. How could
this be the case if there were a lot of scattered protons? (only a few
bounced back, straight back). He realized the atom’s positive charged
particles were contained in the nucleus. The negatively charged
electrons were scattered outside the nucleus at the atom’s edge.
(Discovered protons)
1913 - NIELS BOHR:
Electrons move in definite orbits around the nucleus, much like
planets circle the sun. These orbits, or energy levels, are located at
certain distances from the nucleus.
Each orbit has a limited number of electrons that can occupy that
orbit. These limits are:
1st orbit = 2 e2nd orbit = 8 e3rd orbit = 18 e4th orbit = 32 e5th orbit = 32 e6th orbit = 18 e7th orbit = 8 eWith a special additional limit that no outer most orbit can hold more
than 8 e-.
1932 – JAMES CHADWICK
Discovered neutrons.
ATOMIC MODEL (BOHR-RUTHERFORD MODEL) AS OF 1932:
QUANTUM THEORY (ELECTRON CLOUD THEORY)
Based on their energy and on probability electrons occupy a cloud-like region about the nucleus in which
they will most likely
REVIEW: HISTORY OF A TOMIC STRUCTURE
MATCH
1. _______ Discovered atoms had a nucleus and electrons went around it.
2. _______ Model that says electrons move in “clouds” around nucleus
3. _______ Came up with theory of a “smallest” particle and called it an “atom
4. _______ Thomson’s model of an atom being like a positively charged squish jelly
with negative electrons floating around inside it like raisons
5. _______ An atom can have no more that eight of these
6. _______ Believed there were only four true elements: fire, water, earth, and air.
7. _______ Discovered electrons moved around nucleus in “orbitals.”
8. _______Greek word that means you can’t cut or divide it any further
9. _______ James Chadwick discovered these in 1932
10. _______ Atoms of the same _____________ are alike
11. _______ Created by the joining of more than one element
12. _______ The smallest part of a compound
A. Atom
B.
Molecule
C.
Valence electrons
D. Neutrons
E.
Compound
F. Element
G. Plum Pudding Model
H. Quantum Theory
I.
Democritus, 400 BC
J.
Rutherford, 1903
K. Bohr, 1913
L. Aristotle, 350 BC
ATOMIC STRUCTURE
What are the three main subatomic particles?
99.9% of atomic mass is in nucleus.
Proton, neutron, electron
PROTONS:



positively charged particles in nucleus
The mass of a proton is 1 amu. (atomic mass unit)
# of protons never changes. All atoms of the same element have the same # of protons.
NEUTRONS:



found in the nucleus of the atom
neutral in charge.
slightly more mass than protons but considered to have a mass of 1amu.
ELECTRONS:





a negative charge.
located outside the nucleus
Each level has different amounts of energy
Electrons with lowest energy level are closest to the nucleus.
Mass of an electron is 1/1836 amu
ATOMIC NUMBER:




The number of protons in the nucleus
Determines what the element is.
i.e- an atom of carbon has 6 protons in its nucleus.
Find the atomic numbers on a periodic table. Found on the bottom left corner
ISOTOPES:


atoms of the same element with same number of protons but different numbers of neutrons
The atomic number is same for isotopes of an element.
ATOMIC MASS:




the sum of the protons and neutrons in nucleus.
average mass of all the isotopes of that element
it is usually not a whole number, because it is an ave.
For example, the atomic mass of carbon is 12.011. Found in upper left corner, usually a decimal
The Atoms Family Song
1st Verse:
They’re tiny and they’re
teeny,
Much smaller than a
beany,
They never can be seeny,
The Atoms Family.
Chorus
2nd Verse:
Together they make gases,
And liquids like molasses,
And all the solid masses,
The Atoms Family
Chorus
3rd Verse:
Neutrons can be found,
Where protons hang
around;
Electrons they surround
The Atoms Family.
Chorus
Chorus:
They are so small. (Snap, snap)
They’re round like a ball. (Snap, snap)
They make up the air.
They’re everywhere.
Can’t see them at all. (Snap, snap)
REVIEW: HISTORY OF A TOMIC STRUCTURE
Based on your reading, fill out the chart below
Particle
Charge
Mass (in
amu’s)
Symbol including
charge
Location in atom
Other
proton
electron
neutron
What does amu stand for? __________________________________________
Using the Bohr-Rutherford model, draw a picture of an atom with 3 protons, 2 neutrons, and 3 electrons.
Looking at the periodic table of elements, can you guess what element you drew? _________________________
ISOTOPES & SYMBOLS
TWO DEFINITIONS
1. Atoms whose nuclei contain the same # of protons, but a different # of neutrons
2. Atoms with the same atomic number, but different mass numbers.
Example:
 Hydrogen – 1
 Hydrogen – 2
 Hydrogen – 3
1 p+ 0 no Atomic Number = 1, Mass Number = 1
1 p+ 1 no Atomic Number = 1, Mass Number = 2
1 p+ 2 no Atomic Number = 1, Mass Number = 3
All are isotopes of Hydrogen. The number following the name is the Mass Number for the isotope.
Differences in mass have little effect on an atom’s chemical and physical properties. However, different
isotopes will have very different nuclear properties.
Example:
 Uranium – 235 when hit by a neutron splits to form Krypton, Barium and 3 neutrons while releasing
large amounts of energy.
 Uranium – 238 when hit by a neutron absorbs the neutron to become Uranium – 239.
ISOTOPIC SYMBOLIsotopic symbols are a shorthand way to tell the mass number and atomic number of one atom of an element.
Basic Format:
Example 1:
Example 2:
Mass #
Chemical Symbol
Atomic #
17
O
8
#p+ = 23, #n0 = 28
Atomic # = 23, Mass # = 51, #e- = 23, Element is Vanadium
51
V
Isotopic Symbol is
23
STEPS TO DRAWING ATOMS:
EXAMPLE 1: 21𝐻
1.
Draw a circle to represent the nucleus
2.
Enter the number of protons and neutrons into the nucleus
3.
Draw a circle to represent each orbit needed around the nucleus (the number of
orbits needed is equal to the number of the row the element being drawn is in on
the Periodic Table)
4.
Enter the electrons on each orbit starting from the orbit closest to the nucleus and
working out from there. Be careful to obey Bohr’s limits while adding electrons. (2,
8, 18, Max. 8 in the outer)
EXAMPLE 2:
29
SI
14
Step 1:
Finished model:
Step 2:
Step 3:
or
DRAWING ATOMS WORKSHEET #1
For each atom below list the Atomic Number, Mass Number, # p+, # e-, and #no.
Then draw a Bohr-Rutherford Model of each atom.
1)
24
12
4)
39
19
7)
20
10
10)
33
16
Mg
K
Ne
S
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
2)
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
5)
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
8)
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
11)
9
4
Be
16
8
O
40
19
41
20
K
Ca
Atomic # ______ 3)
Mass #
______
# protons ______
# electrons ______
# neutrons ______
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
6)
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
9)
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
12)
32
16
25
12
40
18
17
8
S
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
Atomic #
______
______
# protons ______
# electrons ______
# neutrons ______
Mg Mass #
Ar
O
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
Atomic # ______
Mass #
______
# protons ______
# electrons ______
# neutrons ______
DRAWING ATOMS WORKSHEET #2
For each atom below write its Isotopic Symbol and name. Draw a Bohr-Rutherford Model of each atom.
1)
13 p+, 14 no
2)
19 p+, 19 no
3)
5 p+, 6 no
4)
6 p+, 8 no
5)
1 p+, 2 no
6)
13 p+, 15 no
7)
2 p+, 2 no
8)
20 p+, 20 no
9)
9 p+, 10 no
10)
18 p+, 21 no
11)
19 p+, 22 no
12)
3 p+, 4 no
DRAWING ATOMS WORKSHEET #3
For each atom below write its Isotopic Symbol and name. Draw a Bohr-Rutherford Model of each atom.
1)
15 p+, 19 no
2)
16 p+, 13 no
3)
15 p+, 20 no
4)
4 p+, 6 no
5)
17 p+, 23 no
6)
10 p+, 7 no
7)
18 p+, 20 no
8)
5 p+, 6 no
9)
20 p+, 19 no
10)
3 p+, 2 no
11)
12 p+, 13 no
12)
20 p+, 21 no
ISOTOPES WORKSHEET #1
List the Name, Atomic Number (# of protons), & Mass Number, for each of the following atoms.
1)
73 Ge
32
2)
118 Sn
50
3) 30 Si
14
4) 190 Os
76
5) 24 Na
11
6) 89 Y
39
7) 15 N
7
8) 184 W
74
9) 126 I
53
10) 173 Yb
70
11) 57 Fe
26
12)
174 Lu
71
ISOTOPES WORKSHEET #2
Write an isotopic symbol for the atoms described below. Name the element.
1) 39 no, 33 p+
2)
136 no, 86 p+
3) 61 no, 47 p+
4) 28 no, 23 p+
5) 149 no, 79 p+
6) 42 n no o, 33 p+
7) 8 no, 9 p+
8) 5 no, 4 p+
9) 21 no, 18 p+
10) 30 no, 27 p+
11) 111 no, 75 p+
12) 120 no, 80 p+
ISOTOPES LOGIC PUZZLE #1
ISOTOPES LOGIC PUZZLE #2
IONS:
Ionization is the process by which an atom becomes “charged,” either positively or negatively.
Normal Atom
#P+ = #eNet charge =
0
The normal state of an atom is neutral due to balance of P+ and e-
Atoms like having their outer shells complete, or” filled.” They will either borrow electrons
from other atoms or give away electrons to make their outer shell full. Gaining or loosing
electrons make and atom into an “ion,” a charged atom. When an atom becomes an ion it is
attempting to arrive at a stable electron configuration.
Ion:
Charged
If an atom gains electrons (e-) it becomes negatively charged
atom
If an atom looses electrons, it becomes positively charged. (It now has more p+ than e-)
The outer shell of an atom is called the “valence shell” and electrons in the outer shell are called “valence
electrons.” If there are less than four valence electrons it is easier for the atom to give away its electrons to
reach a completely filled shell. If there are more than four valence electrons, it is easier for the atom to take
electrons from another atom to fill its outer shell.
Remember: An atom will gain or lose electrons in order to have an outermost orbit of 8 electrons!!!!
It takes work to lose an electron. Recall that just like north and south magnets
are attracted to each other, the electrons are attracted to the protons. To lose
and electron the protons and electrons have to be pulled apart. This work is
called “ionization energy.”
Ionization Energy:
Energy required to
remove electrons
Make the connection: Remember how rubbing your feet on the carpet can create static electricity by friction?
The motion energy your body provides by rubbing is used to loosen the electrons from the atoms in the carpet
and they transfer into your body. Your atoms become negative ions because they have extra electrons.
Remember that the movement of electrons is “electricity” or electrical energy. When the electrons move out of
your body into whatever you shock, your atoms return to neutral.
REVIEW
Draw the atom. Then circle the stable atoms. Put a star next to neutral atoms.
1)
13 p+, 14 no, 10 e2)
19 p+, 19 no, 18 e3)
5 p+, 6 no, 2 e-
4)
6 p+, 8 no, 6 e-
5)
1 p+, 2 no, 1 e-
6)
17 p+, 15 no, 18 e-
CHARGED ATOMS
Directions: For each of the following, determine whether the ion is positive or negative. Write the symbol for the ion with its charge.
Ex. Zinc with 28 electrons. Since: 30 - 28 = +2 Zinc is a positive ion with a symbol of Zn2+
THE PERIODIC TABLE OF ELEMENTS
THE HISTORY OF THE PERIODIC TABLE:
We have been using the periodic table; now let’s take a look at how it was developed. During the 1800’s
chemists were discovering many new elements and found they needed some way to organize the data they
were coming up with.
JACOB BERZELIUS: ABOUT 1800.
He was Swedish. He developed the system for writing chemical symbols.
2-rules:
1. 1st letter in a symbol is always capitalized.
2. If there is a 2nd letter it is always lower case.
DMITRI MENDELEEV:
Russian.
-Developed a table based on atomic mass
-Elements placed in vertical columns
-If an element’s properties didn’t fit in column, he left a space.
What do you think these blanks squares represented?
HENRY MOSELEY: (1912)
-used x-rays to determine atomic # and used it to refine the p. table
PERIODIC LAW:
The law governing the periodic table. Mendeleev stated, “When elements are listed in order of increasing
atomic #, elements with similar properties recur at regular intervals.”
PERIODIC TABLE ARRANGEMENT:
Period:
 horizontal rows on the table numbered 1-7.
 **PERIOD # TELLS YOU HOW MANY ORBITS TO DRAW**
Family or group:
 vertical column on table.
 A group contains elements with similar properties.
 Roman numerals show the families.
 **GROUP # TELLS YOU HOW MANY VALENCE ELECTRONS YOU HAVE**
THREE MAJOR DIVISIONS OF PERIODIC TABLE:
(There is a staircase like ladder running down right side of table)
-Elements on left are metals.
-Elements on right are non-metals
-Elements immediately adjacent to the line dividing metals and non-metals are metalloids (except for aluminum
that is a metal).
METALS: ELEMENTS ON LEFT SIDE OF THE PERIODIC TABLE.
Usual Characteristics:
1. form + ions by giving up electrons.
2. be malleable - able to bend or be hammered without breaking
3. be ductile- able to stretch into wire
4. be solid at room temp (except for mercury)
5. have luster - they are shiny
6. conduct electricity and heat
7. silver colored (except for gold and copper)
8. react with acids
9. react with non-metals
10. they do not react with each other
METALLOIDS: ELEMENTS ADJACENT TO THE STAIR CASE LIKE LINE BETWEEN METALS AND
NONMETALS.
Metalloids have characteristics of both metals and non-metals.
Characteristics:
1. solid at room temp.
2. Poor conductors of electricity at low temperature
3. Good conductors of electricity at high temperatures
Because of the change
in their conductivity
they are referred to as
semiconductors and
they serve as the basis
of computer chips.
NONMETALS: ELEMENTS ON RIGHT SIDE OF THE PERIODIC TABLE. (NOT INCLUDING COLUMN 18
– THE NOBLE GASES).
Characteristics:
1. Form negative ions
2. React with metals
3. Brittle
4. Dull in appearance
5. Poor conductors of heat and electricity
6. Do not react with acids
7. React with each other
FOUR FAMILIES (GROUPS) YOU SHOULD KNOW!




Alkali metals- Group IA
Alkaline Earth Metals- Group IIA
Halogens- Group VIIB
Noble gases- (inert gases). Group O.
ALKALI METALS: FIRST COLUMN ON THE PERIODIC TABLE.
Characteristics:
1. Metals
2. Very soft (can be cut with a butter knife)
3. One electron in outer most energy level (they form +1 ions by losing this
electron).
4. Low Ionization Energy and Electronegativity making it easy to remove
electrons.
5. Highly reactive (react violently with water, acids and peroxides)
6. Reactivity increases going down the family.
7. Form very strong bonds.
ALKALINE EARTH METALS: SECOND COLUMN ON PERIODIC TABLE.
Characteristics:
1. Metals
2. Two electrons in outer shell (form +2 ions by losing both electrons)
3. Ionization energy and electronegativity slightly higher than the alkali metals
4. A little less reactive than alkali metals
5. Reactivity increases down the family
6. Form slightly weaker bonds than the alkali metals.
7. Slightly harder than the alkali metals
HALOGENS: NEXT TO LAST COLUMN ON PERIODIC TABLE.
Characteristics:
1. Non-metals
2. Seven electrons in outer energy level (gain 1 electron to
become –1 ions)
3. very high ionization energy and electronegativity making
it easier for them to gain electrons.
4. Highly reactive
5. Reactivity increases going up the family
6. React with all elements on the periodic table except Helium, Neon and Argon
7. Do not occur as individual (unbonded atoms) in nature
Halogens will form a “diatomic molecule” – a molecule made up of 2 atoms of the same element.
There are seven elements that will form diatomic molecules any time they are present in their pure form. These
elements are:
 Hydrogen (H2)
 Nitrogen (N2)
 Oxygen (O2)
 Fluorine (F2)
 Chorine(Cl2)
 Bromine(Br2)
 Iodine(I2)
Remember them with: “Harry’s brother Ike found no candy outside.”
NOBLE GASES: LAST COLUMN ON PERIODIC TABLE
Noble gases have complete outer energy levels (8 e- in their outer energy level, except Helium which has 2e- in its
only energy level, remember the 1st energy level is filled with 2 e-). They wont mix with other elements easily
because they’re energy levels are complete. That’s why their “Nobel” gasses- they don’t mix with “common”
elements.
Characteristics:
1. Stable electron arrangement (the outer energy level is filled)
2. Extremely high Ionization Energy
3. Tend not to form ions
4. Inert - tend not to take part in chemical changes
5. Very low melting points and boiling points making them gases at room temperature.
SOME REVIEW:
Transition elements: or the d-block. We will not be using these in class. These elements have suborbitals that
act like valence electrons and are hard to determine behavior
Most likely groups to give up electrons?
Metals because they have a lower group #, it is easier to give up a few than gain a lot
Most likely to gain/grab electrons?
Non-metals because they are close to 8 (a full valence shell). It is easier to get a few than give up a lot.
If an element gains an electron it becomes negative, if it loses one it becomes positively charged.
When you turn on a light for example, you are exciting the electrons in the filament by sending an electric current
through the wire. The activity of the electrons moving from shell to shell causes a release in energy seen as light
and felt as heat as the electrons fall back to their positions.
PERIODIC TABLE PUNS #1
Use your imagination and the elements in the Periodic Table to solve each pun!
Example: Five cents -
Nickel
Ni
1. What you do in a play
_________________________ __________
2. What you do to a wrinkled shirt
_________________________ __________
3. “Tasty” part of your mouth
_________________________ __________
4. Someone who likes to start fires
_________________________ __________
5. Superman’s weakness
_________________________ __________
6. Your brother or mine
_________________________ __________
7. Extinct
_________________________ __________
8. Imitation diamond
_________________________ __________
9. A type of flower
_________________________ __________
10. Las Vegas lights
_________________________ __________
11. Police
_________________________ __________
12. Golden State
_________________________ __________
13. Name of a goofy convict
_________________________ __________
14. Mr. Mony's enemy
_________________________ __________
15. What you do to flowers
_________________________ __________
16. What you did to ripped jeans
_________________________ __________
17. A “prize” element
_________________________ __________
18. A very smart person
_________________________ __________
19. Person from the big blue planet
_________________________ __________
20. A fur seller
_________________________ __________
PERIODIC TABLE PUNS #2
Use your imagination and the elements in the Periodic Table to solve each pun!
1. Not an exciting person
_________________________ __________
2. Thanksgiving guests
_________________________ __________
3. Get clean with this
_________________________ __________
4. Drive away in style in a ____
_________________________ __________
5. Does a body good
_________________________ __________
6. Proud to be an _____
_________________________ __________
7. Mickey’s pal
_________________________ __________
8. Warrior Princess
_________________________ __________
9. A nice guy
_________________________ __________
10. Someone who loves computers
_________________________ __________
11. The first person in a race has the ___
_________________________ __________
12. E = mc2
_________________________ __________
13. This man followed the yellow brick road
_________________________ __________
14. How to tell a secret
_________________________ __________
15. Monday night TV show
_________________________ __________
16. A phrase from Dr. Suess
_________________________ __________
17. What a doctor does to his patients
_________________________ __________
18. Part of a whole
_________________________ __________
19. Place for washing dishes
_________________________ __________
20. Drink in an Al can
_________________________ __________
21. Happens when you lasso a horse
_________________________ __________
22. What a dog does with a bone
_________________________ __________
23. A sinking ship
_________________________ __________
24. What a cloud does
_________________________ __________
ELECTRON DOT MODELS (LEWIS STRUCTURES )
Def - A simple model of the atom that can be used to illustrate chemical bonding
Electron dot models consist of the Chemical symbol of the element surrounded by the valence electrons.
Example: Sodium
The Bohr-Rutherford model for sodium is:
This atom has only one valence electron so the electron dot model would be
Rules:
1. No more than 2 electron dots per side
2. Do not pair electron dots until there is one dot per side
TRY THESE!
Draw Lewis Dot structures around the elements. Remember to ONLY draw the electrons in the outer shell.
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Ga
Ge
As
Se
Br
Kr
IONIC AND COVALENT BONDING
IONIC BONDS
Ionic Bond: a chemical bond due to the transfer of
electrons between a metal and a non-metal and their
resulting attractions.
For example, common table salt is sodium chloride.
When sodium (Na) and chlorine (Cl) are combined, the
sodium atoms each lose an electron, (Na+), and the
chlorine atoms each gain an electron (Cl−). These ions are
then attracted to each other in a 1:1 ratio to form sodium
chloride (NaCl).
Na + Cl → Na+ + Cl− → NaCl
COVALENT BONDS
Covalent Bond: a chemical bond due to a sharing of electrons between two non-metals. OR a non-metal and
hydrogen.
Neither atom wants to give up its electrons to the other, so they share. The shared electrons stay between
them, forming a very strong bond. They can share one, two, or three electrons forming single, double, or triple
bonds. They can also share electrons between more than 2 atoms.
Examples: F2 (this is two flourine atoms in a covalent bond)
H2O (two hydrogen atoms with one oxygen atom)
CH4 (this is carbon and 4 hydrogens)
Diatomic molecules are covalently bonded:
List the seven diatomic molecules here:
IONIC AND COVALENT COMPOUNDS
Ionic Compounds
Covalent Compounds
Made up of ions created by a transfer of electrons
from a metal to a nonmetal
Made up of molecules created by the sharing of
electrons by nonmetals.
Crystalline solid
Molecular compounds.
Formula indicates the ratio between the ions in the
crystal.
Formula indicates the actual number of atoms of each
element in each molecule
High overall attractions (all + ions attract all - ions; all ions attract all + ions) resulting in high mp and bp and
low volatility (all are solids at room temperature)
Strong attractions between atoms within a molecule
(due to overlap of valence orbits), but low attraction
between molecules resulting in low mp and bp and
high volatility (most are liquids or gases at room
temperature)
Tend to be water soluble
Tend to be alcohol soluble
Electrolytes - substances that conduct electricity in
solution (due to the presence of free ions)
Nonelectrolytes - Substances that do not conduct
electricity in solution (no free ions)
ELECTRON DOT MODELS AND BONDING
Determine the formulas for the compounds formed by the following pairs of elements by drawing electron dot models
showing the electron transfers.
1) Lithium (1 dot) + Bromine (7 dots)
2) Hydrogen (2 dots) + Oxygen (6 dots)
3) Hafnium (4 dots) + Oxygen (6 dots)
4) Scandium (3 dots) + Sulfur (6 dots)
5) Sodium (1 dot) + Chloride (7 dots)
6) Technetium (7 dots) + Iodine (7 dots)
7) Zinc (2 dots) + Phosphorus (5 dots)
CHEMICAL REACTIONS
LAW OF CONSERVATION OF MASS
ACIDS, BASES, AND SALTS:
ACIDS
Acids are compounds that releases H+1 ions in solution
Characteristics of acids:
1. Sour taste like lemon juice
2. Water Soluble
3. Electrolytes- substances that conduct electricity when in solution due
to free ions
4. React with metals to release H2 gas
5. React with carbonates to form a salt
6. React with metal and causes oxidation
7. React with bases to form a salt and water (this is called
neutralization)
8. Changes litmus paper red
9. pH less than 7.0
Common Acids:
Hydrochloric Acid (HCl)
Sulfuric Acid (H2SO4 )
Lemon Juice (Citric Acid)
Nitric Acid (HNO3)
Vinegar (Acetic Acid)
BASES
Bases are substances that release OH- (hydroxide ions) in solution
Characteristics of bases:
1. Bitter taste
2. Water Soluble
3. Slippery to touch (i.e. soap)
4. Emulsify fats and oils (break into drops and hold suspended in
solution)
5. Electrolytes
6. React with non-metal and causes oxidation
7. React with calcium and magnesium compounds
8. React with acids (neutralization)
9. Changes litmus paper blue
10. pH greater than 7.0
Common Bases:
Sodium Hydroxide (NaOH)
Potassium Hydroxide (KOH)
Ammonium Hydroxide (NH4OH)
Calcium Hydroxide (Ca(OH)2)
Magnesium Hydroxide (Mg(OH)2)
SALTS
Salts are compounds containing a metallic ion (+ ion) and an acid-radical ion (-ion)
(Metallic ion is any + ion other than H+; Acid-radical ion is any –ion other than OH-)
Characteristics of salts:
1. Water Soluble
2. Salty taste
3. Solid at room temperature
4. High melting point
5. Electrolytes
6. pH around 7.0
INDICATORS
Indicators are chemicals that change color in the presence of H+ or OH- ions.
Indicators can be used to tell:
a. If a substance is an acid or base
b. Strength of an acid or base
Common indicators:
 Litmus paper: red in acid, blue in base
 Phenolphtalein: colorless in acid, pink in base
 Hydrine paper: color varies depending upon the strength of the acid or base
PH SCALE
Acid/base strength is measured on a scale called the ph scale. pH stands for “ % of H+”
←Acid
Base→
│-------------------------│-------------------------│
0
7.0
14
Neutral
Strength increases moving away from 7.0
REVIEW QUESTIONS
(D10)(PCAPT)Which substance cannot be decomposed into
simpler substances?
A. Ammonia
B. Aluminum
C. Methane
D. Methanol
(D6) A positively charged particle will:
A. repel a negatively charged particle
B. attract a negatively charged particle
C. attract a positively charged
D. run in fear from a neutral particle
(D10)(PCAPT)The chemical properties of an element are
determined by its
A. Atomic mass
B. Proton number
C. Electron arrangement
D. Atomic size
D10)(PCAPT) Oxygen has an atomic number of 8. Which of
the following elements would you expect to be MOST similar
to oxygen in terms of its chemical properties?
A. Nitrogen (N)
B. Fluorine (f)
C. Sulfur (S)
D. Chlorine (Cl)
(D10) In order for an atom to be neutral the:
A. number of protons = the number of electrons
B. number of protons = the number of neutrons
C. number of electrons = the number of neutrons
D. number of protons > than the number of electrons
(D10) Atom A has 5 protons and 5 neutrons; atom B has 5
protons and 6 neutrons. The atoms are:
A. isotopes of the same element.
B. atoms of different elements.
C. different sizes
D. different in their properties
(D10)(PCAPT)What do the elements carbon, silicon,
germanium and tin have in common?
A. They are metals
B. They are in the same period
C. They have the same number of electrons
D. They have four electrons in their outer shell
For the next 3 questions refer to the drawing below.
(D10) The mass number of this same atom is:
A) 6
B) 16
C) 17
D) 33
(D10) This atom would have ____ valence electrons.
A) 4
B) 5
C) 6
D) 7
(D10) If another isotope of this element existed with a Mass
Number of 30, it would differ from the one shown in the
number of which particle?
A. protons
B. neutrons
C. electrons
D. all of the above
(D10) The maximum number of electrons in the outer orbit of
any atom is:
A) 2
B) 8
C) 10
D) 14
(D10)(PCAPT)Nitrogen has an atomic number of 7 and an
atomic mass of 14.01. Which of the following is most true of
nitrogen?
A. Each atom of nitrogen has 7 protons and 7 neutrons
B. Each atom of nitrogen has 7 protons and 14
neutrons
C. Each atom of nitrogen has 14 protons and 14
neutrons
D. Each atom of nitrogen has 7 protons and 14
neutrons
(D10)(PCAPT) The atomic number of iron is 26, and the
atomic mass is 55.847. What do these numbers mean in
regard to protons, electrons and neutrons?
A. There are 26 each of protons and neutrons, and the
rest of the mass is the result of electrons.
B. There are 26 protons and 26 electrons. Some atoms
of iron have 29 neutrons; the 0.847 shows that there
is more than one isotope of iron.
C. There are 26 protons and 29 neutrons. Each particle
has an atomic mass of 1.
D. There are 26 protons and 26 neutrons. Since
neutrons have slightly more mass than protons, the
mass is greater than 52.
For the next 3 questions refer to the symbol drawn below.
238
U
92
(D10) What is the mass number of the atom represented by
this symbol?
A) 92
B) 146
C) 238
D) 330
(D10) What is the atomic number of this atom?
A) 92
B) 146
C) 238
D) 330
(D10) This symbol is referred to as a(n):
A. Formula Symbol
B. Isotopic Symbol
C. Atomic Symbol
D. Ionic Symbol
(D10) In the drawing to
the right, the atoms all
belong to what family?
A. Nobel Gasses
B. Alkaline Earth
C. Halogen
D. Alkaline Metals
(D10) In order to be identified as the element carbon (C), an
atom must have ______.
A. 6 protons
B. 6 neutrons
C. 12 electrons
D. 12 electrons
(D10) Oxygen has an atomic number of 8. Which of the
following elements would you expect to be most similar to
oxygen in terms of its chemical properties?
A. Nitrogen (N)
B. Fluorine (F)
C. Sulfur (S)
D. Chlorine (Cl)
(D10) Group I (the alkali metals) includes lithium (Li), sodium
(Na), and potassium (K). These elements have similar
chemical properties because they have the same
__________.
A. numbers of protons and neutrons
B. numbers of electrons in the outer energy level
C. numbers of protons in the nucleus
D. numbers of neutrons in the nucleus
(D10) Metals and nonmetals generally form ionic bonds with
each other. Which of the following sets of elements will most
likely for an ionic bond?
A. Na, F
B. Cl, F
C. Na, K
D. He, O
(D10) The chemical properties of an element are determined
by its
A. atomic mass.
B. proton number.
C. electron arrangement.
D. atomic size.
(D10) Study the table below. Which atom has a net positive
charge?
A.
B.
C.
D.
Atom W
Atom X
Atom Y
Atom Z
(D10) Which element in the table above has the highest
atomic mass?
A. Atom W
B. Atom X
C. Atom Y
D. Atom Z
(D10) Which of the following is the most important factor in
determining an element’s place in the periodic table?
A. number of protons
B. number of neutrons
C. atomic charge
D. atomic density
(D10). Elements in the same family all have the same:
A. Atomic Numbers
B. number of valence electrons
C. valence energy level
D. number of protons
(D10) On the Periodic Table the elements are arranged by:
A. Atomic Number
B. Mass Number
C. number of neutrons
D. number of isotopes
(D10) An element that shows characteristics of both metals
and nonmetals is:
A. an alkaline earth metal.
B. a noble gas
C. a metalloid.
D. a halogen.
(D10) An element conducts electricity and heat, and has high
luster. It is probably a:
A. Metal
B. Nonmetal
C. Liquid
D. Gas
(D10)(PCAPT) The mass of an element is determined mainly
by its
A. Atomic number
B. Number of protons and neutrons
C. Electron arrangement
D. Atomic size
(D11) Which of the following is best classified as a
compound?
A. Helium (He), because it contains only one type of
atom
B. Oxygen ( O2 ), because it contains two of the same
type of atoms
C. Carbon dioxide (CO2), because it contains two
different types of atoms
D. Manganese (Mn), because it contains a metal and a
nonmetal
(D11) In general, the force that holds atoms together in a
compound is called
A. gravity
B. magnetism
C. chemical bond
D. electronegativity
(D11) The formation of a chemical bond involves
A. only the protons
B. electrons & neutrons
C. protons & electrons
D. only the electrons
(D11) When an atom becomes an ion it is attempting to:
A. gain electrons
B. lose electrons
C. share electrons
D. obtain a complete valence energy level
(D11) To become a +3 ion, an atom must:
A. gain 3 electrons
B. lose 3 electrons
C. gain 3 protons
D. lose 3 protons
(D11) The chemical properties of elements are determined
by the gain, loss, or sharing of:
A. electrons
B. ions
C. protons
D. neutrons
(D11) A covalent bond would most likely be formed between
Fluorine and:
A. Sodium
B. Oxygen
C. Magnesium
D. Helium
(D11) A bond due to a transfer of electrons from a metal to a
nonmetal is a(an):
A. physical bond
B. ionic bond
C. covalent bond
D. metallic bond
(D11) An ionic compound forms between a
A. metal & nonmetal
B. nonmetal and nonmetal
C. metalloid and nonmetal
D. metal & metal
(D11) An atom gains two electrons to have a ___ charge.
A. +2
B. +4
C. -2
D. 0
(D11) Two atoms that are sharing a pair of electrons have
formed a(n) _______ bond.
A. Ionic
B. James
C. Covalent
D. Cooperative
(D11)(PCAPT)When a metal atom combines with a nonmetal
atom, the nonmetal atom will
A. Lose electrons
B. Share electrons
C. Grain electrons
D. Not change its number of electrons
(D11)(PCAPT)A balanced chemical equation reflects the idea
that the mass of the products
A. is greater than the mass of the reactants
B. Is less than the mass of the reactants
C. Equals the mass of the reactants
D. Is not related to the mass of the reactants
(D11) In a simple chemical compound the total charge must
add up to:
A. an even number
B. zero
C. an odd number
D. eight
(D12) Which of the following has the most H+ ions present?
A. strong acid
B. weak acid
C. strong base
D. weak base
(D12) An acid's properties are due to the presence of:
A. Na+ ions
B. OH- ions
C. H+ ions
D. Cl- ions
(D12) Which of the following has the most OH- ions present?
A. strong acid
B. weak acid
C. strong base
D. weak base
(D12) The pH of a salt is around:
A. 1.4
B. 7.0
C. 10.2
D. 14.0
(D12) When an acid and base react, the resulting solution has
a pH around:
A. 1.0
B. 6.0
C. 7.0
D. 12.0
(D12) The safest way to test for an acid or base is:
A. see how it reacts
B. tasting it
C. touching it
D. using an indicator
HCl + NaHCO3 → NaCl + CO2 + H2O
(D12) A base is a compound that contains:
A. CO32- ions
B. OH- ions
C. H+ ions
D. O2- ions
(D12) A material, such as Cabbage Juice, that changes color in
an acid, or base is called a(n):
A. chameleon
B. acid
C. base
D. indicator
(D12) pH scale ranges from 0 to:
A. 7
B. 10
C. 14
D. 20
(D12) The pH that indicates the strongest acid is:
A. 0.6
B. 6.3
C. 7.0
D. 10.5
(D12) Antacids contain bases that react with the acid in your
stomach to relieve indigestion. In the reaction above,
NaHCO3 reacts with the strong hydrochloric acid, HCl, to form
a salt, carbon dioxide, and water. This type of reaction is
called
A. dehydration
B. oxidation
C. titration
D. neutralization
(D12) Determine if the following are acids, bases or neutral.
If the compound is an acid or base indicate if it is weak or
strong.
Solution A has a pH of 11.4 ________________________
Solution B has a pH of 6.3 _________________________
Solution C has a pH of 4.3 ________________________
Solution D has a pH of 7.0 ________________________
Solution E has a pH of 8.2 _________________________
(D12)(PCAPT) When an acid and a base react with each other
__________and ___________are produced.
A. Salt and CO2
B. Hydrogen and heat
C. Salt and water
D. Heat and oxygen
(D12) One property of bases is that they:
A. are nonelectrolytes
B. react with metals to produce Hydrogen gas
C. taste bitter
D. turn litmus red
(D12) A compound contains a metal and a nonmetal. The
compound would be a(n):
A. salt
B. covalent compound
C. acid
D. base
(D12) One property of salts is that they taste:
A. salty
B. sweet
C. sour
D. bitter
(D12) An indicator determines the presence of an acid, or a
base by:
A. producing bubbles
B. giving off an odor
C. changing color
D. burning brightly
Which of the following is an example of a chemical reaction?
A. Aluminum foil being cut into smaller pieces
B. A drop of food coloring dissolving in water
C. Melted butter becoming a solid when placed in the
refrigerator
D. The surface of a copper penny changing color after
being in a drawer for years
Which of the following ALWAYS results from a chemical
reaction?
A. Fire
B. Bubbles
C. A new substance that is a solid
D. A new substance that can be a solid, liquid, or gas
A student placed a liquid in a jar and sealed it. Then she
heated the liquid and it turned into a gas. If the number of
atoms in the sealed jar stayed the same, what happened to
the mass of the jar and everything inside it after she heated
it?
A. The mass increased.
B. The mass decreased.
C. The mass stayed the same.
D. It depends on whether a chemical reaction occurred.
A student places some baking soda and a jar of lemon juice in
a plastic bag and seals the bag. She weighs the bag and
everything in it. She shakes the bag so that the lemon juice
spills out of the jar and mixes with the baking soda inside the
bag. The student observes that bubbles form and the bag
expands.
If the student weighs the bag and everything in it after the
bubbling stops and compares the final weight to the starting
weight, what will she find out?
A. The final weight will be greater than the starting
weight because new atoms are produced during the
experiment.
B. The final weight will be less than the starting weight
because some of the atoms are destroyed during the
experiment.
C. The final weight will be the same as the starting
weight because the number of each kind of atom
does not change during the experiment.
D. The final weight will be the same as the starting
weight because some atoms are destroyed, but new
ones are created during the experiment.
A student adds water and sugar to a jar and seals the jar so
that nothing can get in or out. The student then weighs the
jar containing the water and sugar. After some sugar
dissolves, the student weighs the jar and its contents again.
Using the information about the five liquids in the table
below, which of the following liquids could be the same
substance?
Volume
Boiling Point
Flammable
(mL)
(°C)
What will happen to the weight of the jar containing the
water and sugar after some of the sugar dissolves?
A. The weight will stay the same.
B. The weight will increase.
C. The weight will decrease.
D. The weight will depend on how much sugar
dissolves.
In the diagrams below, sulfur atoms are represented by gray
circles, carbon atoms are represented by black circles, and
oxygen atoms are represented by white circles.
Which of the following could be a product of the chemical
reaction between sulfur and oxygen?
A.
B.
C.
D.
Which of the following could represent a chemical reaction?
Atoms are represented by circles, and molecules are
represented by circles that are connected to each other. The
different colored circles represent different kinds of atoms.
A.
B.
C.
D.
Color
Liquid 1
25
no
100
colorless
Liquid 2
50
no
100
colorless
Liquid 3
25
yes
100
colorless
Liquid 4
25
no
78
colorless
Liquid 5
25
no
100
yellow
A.
B.
C.
D.
Liquids 1 and 2
Liquids 1 and 3
Liquids 1 and 4
Liquids 1 and 5
Which of the following is an example of a chemical reaction?
A. Water evaporating from a pot on a hot stove
B. Sand being removed from sea water by filtration
C. A spoonful of sugar dissolving in a glass of water
D. A white solid forming when two clear liquids are
poured together