AP Chemistry Notes – Chapter 2
Chemistry Notes – Chapters 5 & 7
Atoms and Elements
What is sciences view on the cosmic origin of the elements that we
take for granted in our environment and lives?
 “Big Bang” Theory: (grapefruit sized sphere of matter exploded 15 billion years ago
creating a cloud with a temperature of 1030 K, filled with protons, neutrons, and electrons. The
cloud then cooled and the protons, neutrons and electrons began to form helium and hydrogen)
 The Sun:
After thousands of years it is believed that the hydrogen and helium condensed
into stars like our sun. Each second in the sun 700 million tons of hydrogen is converted into 695
million tons of helium and 3.9 x 1026 joules of energy. The mass that appeared lost was converted
to pure energy (E = mc2).
H
+
H

He
+
Energy
Fusion
 Supernovas:
Exploding stars observed by us are called supernovas. Supernovas can be
thought of as factories for heavier elements (elements larger than hydrogen and helium). It is
thought the heavy elements produced from these supernovas move out through space and
gradually condense into planets like Earth
2.1 Protons, Electrons, and Neutrons: Atomic Theory
A. Many of the experiments that have led to our current MODEL of the atoms involved:
1. Electricity (1700’s) – Benjamin Franklin
o
o
o
Identified the existence positive (+) and (-) charges
Opposite charges neutralize each other
Like charges repel each other while unlike charges attract one another
2. Radioactivity (1899) – Henri Becquerel and Madame Curie
o Uranium emitted rays that were named radioactivity, substances that emitted these rays are said to be
radioactive.
o Madame Curie isolated polonium and radium that emitted radioactivity
Positively Charged Plate
+
Radioactive
Source
Detector
Plate (Film)
Negatively Charged Plate
Alpha Radiation (α) - Large massed particles, charged with a +2 charge
Beta Radiation (β) - Small massed particles, with a –1 charge
Gamma Radiation (γ) - No charge or mass
1
B. The Nuclear Model of the Atom
 All matter is made up of tiny particles called atoms
 An atom is more than 1 000 000X smaller than the thickness of a single hair on your head.
 Atoms have the same basic parts
Atom
Most of the Mass
Most of the space
Nucleus
Neutrons
Uncharged
Particles
(nucleons)
Electron
Cloud
Protons
=
Electrons
Positively Charged
Particles
Negatively Charged
Particles
Electrically Neutral
C. Experiments Leading to “NUCLEAR MODEL” of the Atom
Scientist
Description
Name of Experiment
John Dalton
(1780’s)
Dalton’s Atomic Theory (model)
Dalton’s Atomic Theory
*1) All elements are composed of tiny
indivisible particles called atoms
*2) Atoms of the same element are identical.
Atoms of any one element are different from
any other element.
3) Atoms of different elements can physically
MIX together OR can CHEMICALLY COMBINE
with one another in whole-number ratios to
make compounds.
Outcome
4) Chemical reactions occur when atoms separated,
joined or rearranged. Atoms of one element are
never changed into atoms of another element as
a result of a chemical reaction
*Later proved wrong by other observations and experiments
2
JJ Thompson
(1876)
A beam of electrons (cathode rays)
passes through an electric and
magnetic field and were deflected
away from the negative plate
Cathode Ray Experiment
*electrons
discovered
*charge to
mass ratio
electrons
*protons
discovered
Thompson’s Cathode Ray Experiment
Eugene Goldstein
(1876)
A beam of protons (canal rays)
passes through an electric and
magnetic field and were deflected
away from the positive plate
Canal Ray Experiment
Robert Millikan
(1912)
Oil drops that had electrons
adhered to them fell between two
charged plates, by adjusting charge
an the plates and by using Thompson’s
charge to mass ratio he determined the
mass and charge of an electron
Oil Drop Experiment
* Mass of
an electron
9.11 x 10-28g
*Charge of
an electron
-1.60 x 10-19 C
Millikan’s Oil Drop Experiment
3
Ernest Rutherford
A beam of positive alpha (α) was directed
at a piece of thin gold foil. A screen was
was used to detect particles passing
through. Most alpha particles passed
through but some were deflected from
their path (even backwards) by the
dense, positively charged nucleus of
some of the gold atoms.
Gold Foil Experiment
*nucleus
discovered
Rutherford’s Gold Foil Experiment
Where did all these experiments on the atom leave us???????
NUCLEAR MODEL of the Atom:
4
Review
The following scientists and the research that they carried out was pivotal in creating the Nuclear Model (Theory)
of the atom. Please match the experiment and finding on the left with scientist on the right :
______ a) Oil Drop Experiment; Using charge/mass ratio from cathode
ray studies the mass and charge of an electron was determined
______ b) Gold Foil Experiment; Alpha particles directed at a piece of gold
foil were deflected supporting the existence of a dense positively
charged nucleus.
______ c) Canal Ray Experiment; Bema of proton rays (canal rays) were passed
through an electric field and were deflected away from the positive
plate supporting the existence of protons
______ d) Cathode Ray Experiment; A beam of electrons were passed
through an electric field and were deflected away from the negative
plate supporting the existence of electrons
a) Eugene Goldstein
b) Robert Millikan
c) JJ Thompson
d) Ernest Rutherford
2.2 Atomic Number and Atomic Mass
A. Atomic Number (Z)
The number of protons in the nucleus of an atom of an element is its atomic number, given the symbol Z.





All atoms of the same element have the same number of protons in the nucleus.

The number of protons in an atom of any element can be found on the periodic table:
Atoms of an element have the same number of protons as electrons making them ___________________.
Chemical properties (how atoms react) of an element depends on the number of electrons in its atoms.
The identity of an atom can be determined from the number of the protons in the nucleus.
Hydrogen is the simplest element, its atoms only have one proton in their nucleus
Atomic Number (Z)
29
Cu
63.546
Practice:
a) How many protons in an atom of uranium?_________
b) Atoms are neutral (have no net charge), knowing this how many electrons do you think a uranium atom
would have?___________
c) What type of element has atoms that contain 20 protons?
__________________
d) What type of element has atoms who electron clouds contain 7 electrons? __________________
B. Relative Atomic Mass and the Atomic Mass Unit
What is the mass of an atom of an element?
 Masses of atoms are always determined RELATIVE to the carbon atom that is made up of 6 protons,
6 neutrons, and 6 electrons. This carbon atom has been assigned a mass of EXACTLY 12.000
atomic mass units (amu).
 One atomic mass unit, 1 amu, is 1/12th the mass of carbon atom that is made up of 6 protons, 6
neutrons, and 6 electrons.
 The “amu” can be related to the gram by the following conversion factor: 1 amu = 1.661 x 10-24 g
5
For example:
An oxygen atom has been found to be 1.33X the mass of a carbon atom with 6 protons, 6 neutrons and 6
electrons (12.00 amu). What is its mass in amu’s? grams?
C. Mass Number (A)
Mass
Particl e
Electron
*Proton
*Neutron
Grams
9.109 x 10-28
1.673 x 10-24
1.675 x 10-24
Relative Mass (amu)
0.00549
1.01
1.01
Charge
-1
+1
0
Symbol
e1p1+
n0
*Protons and neutrons have masses very close to 1 amu
The sum of the number of protons and neutrons for an atom is called its mass number and is given the
symbol A.
Determine the mass of ONE Atom in amu and g’s
6
Examples:
1) A sodium atom has 11 protons and 12 neutrons in its nucleus what is its:
mass number (A) ?_____ atomic number (Z)?______ How many electrons would it have?________
2) An atom is made up of 16 protons, 16 neutrons, and 16 electrons. Using your periodic table what is the
identity of the element (Symbol)?_________ Mass number (A)?_______ Atomic number (Z)?_______
3) a) Identify the following atoms…
17 e-
______________
________________
b) Why is the electron cloud of the atom with 17 e1- larger than the atom with 10 e1-?
3) Complete the table assuming all species are atoms:
Name
Symbol
Atomic
Composition of Nucleus (nucleons)
Number
Protons
Neutrons
(Z)
Iron
________
_________ ________
_______
80
___________
___________
___________
120
Mass
Number
(A)
Number of
Electrons
56
_________
_______ _________
_________ ________
_______
47
___________
_______
47
_________
_______
___________
___________
207
_________
_______
___________
31
59
_________
Pb
_________ ________
C. Symbolizing Atoms of Various Elements
Atoms of various elements can be symbolized using
X NOTATION
Mass Number
Symbol
Atomic number
X NOTATION or HYPHEN NOTATION:
HYPHEN NOTATION
A
X
Z
Element Name – Mass#
Example : The most common atom of uranium has 92 protons, 146 neutrons and _______electrons.
Symbolize this atom using both techniques described above:
7
Practice:
a) What is the mass number of a calcium atom with 24 neutrons? Symbolize using both methods?
b) Identify the element who’s atoms are identified…
i.) with the following symbol
31
??
15
ii) as having 13 electrons and a mass number of 27
iii) as having (Z) = 19 and (A) = 39.
_________________________
_________________________
_________________________
c) What is the identity of an element whos atoms have 90 protons and 142 electrons? Symbolize using
both methods?
d) Complete the table:
X-NOTATION
80
35
??
Protons
HYPHEN NOTATION
___________________ _______
________
Sulfur-32
_______
Neutrons
Electrons Atomic # Mass #
(Z)
(A)
________
________ ______ _______
________
________ ______ _______
2.3 Isotopes
??
Only in VERY few instances (for example, aluminum,
fluorine, and phosphorous) do all atoms of the same
element have the same mass. Most elements consist of
atoms having different mass numbers. Atoms with the same
atomic number (number of protons) but different mass
numbers (different number of neutrons) are called
isotopes.
Sample of Neon Atoms
??
??
Symbol
Notation _____________
_______________
______________
8
Identifying and Quantifying Isotopes of an Element – The Mass Spectrometer
 The mass number of an isotope is an approximation of the exact atomic mass of the isotope.
 The masses of isotopes of an element and their percent abundance experimentally determined
using a MASS SPECTROMETER.
The mass spectrometer is an analytical instrument used to measure atomic masses (mass of atoms) and molecular
masses (masses of molecules) directly.
A. Isotope Abundance
o
o
Isotope
Mass
(amu)
Relative
Percent
Abundance Abundance
______
19.9924
________
________
______
20.9940
________
________
______
21.9914
________
________
Important points regarding exact atomic masses:
The exact mass of any isotope of an element is not an integral (whole) number (except
for carbon-12, which is EXACTLY 12.000 by definition).
The exact mass of any atom is slightly less than the sum of the masses of protons,
neutrons, and electrons in the atom. This difference is sometimes called the mass defect,
and is related to the mass that was converted to energy (E = mc2) to bind the particles
found in the nucleus (protons and neutrons) together.
9
B. Using Mass Spectrometer Data to Calculate the Atomic Weight of an Element
The atomic weight an atom of an element must be somewhere between the exact atomic masses of each
isotope. The atomic weight of an element is a weighted average of the exact masses of each
isotope of an element. This is why atomic weights are NEVER whole numbers.
Atomic =(relative abundance Isotope 1)(Exact Mass Isotope 1) + (relative abundance Isotope 2)(Exact Mass Isotope 2). . .
Weight
Practice:
1. If you could count out 10,000 boron atoms from a natural sample 1991 of them would be boron-10 and
8009 of them would be boron-11 atoms. The percent of a certain isotope in a sample of a naturally
occurring element is termed percent abundance.
RELATIVE ABUNDANCE
Percent Abundance = number of atoms of a given isotope
total number of atoms sampled
X 100% = PERCENT ABUNDANCE
X 100% =
a. Calculate the abundance of each isotope of Boron:
Isotope Relative Mass
Boron
Sample
8009
10 000 Boron atoms
1991
Relative
Abundance
Percent
Abundance
11
B
5
or
Boron-11
11.0093 amu
___________
____________
10
B
5
or
Boron-10
10.0129 amu
___________
____________
Total
___________
____________
b. Calculate the weighted average atomic mass of Boron:
10
2. a) Argon has three isotopes with 18, 20, and 22 neutrons, respectively. What are the mass numbers
and symbols of these three isotopes?
b) Gallium has two isotopes: Gallium-69 and Gallium-71.
i) How many protons and neutrons are in the nuclei of each isotope?
Protons
Neutrons
Gallium-69
_______
_______
Gallium-71
_______
_______
ii) If the abundance of Gallium-69 is 60.1%, what is the abundance of Gallium-71?_____
Mass Defect Problem (E = mc2)
You might expect the mass of a deuterium (2H), would be the sum of the masses of one proton and one
neutron
Mass of proton
+
Mass neutron
=
Mass Deuterium Atom
1.007276 amu
1.008665
2.015941
However the actual mass of 2H (which is actually measured to be 2.01355 amu using a mass
spectrometer) is LESS than the some of its constituents. Where did the mass disappear to?
=
=
=
Actual mass of Deuterium
-
Theoretical mass of Deuterium
________________amu
The”missing mass” is converted to energy, the binding energy (E= mc2)
2.4 Atomic Weight (Mass) of Elements

The mass shown on the periodic table is the weighted average of the exact masses of each isotope
of an element
29
Cu
63.546

The mass shown on the periodic table when rounded is indicative of the most abundant isotope of an
element.

ISOTOPES OF THE SAME ELEMENT CHEMICALLY REACT IDENTICALLY.
11
Practice Calculating the Atomic Weight of an Element:
Using the percent abundance and atomic masses of each of nitrogen’s isotopes given on page 8 of this
packet of notes, calculate the average atomic mass of nitrogen.
Calculating the Abundances of an Isotope
The element europium exists in nature as two isotopes: europium-151 which has a mass of 150.9196 amu
and europium-153 which has a mass of 152.9209. The weighted average atomic mass of europium is
151.96 amu. Calculate the relative abundance of each isotope of europium
Element
Symbol
Atomic Weight
Mass Number
Isotopic Mass
Abundance
(weighted avg)
(amu)
Europium
Eu
151.96
151
153
150.9196
152.9209
_______%
_______%
12
Practice Calculating the Abundance of Isotopes of an Element:
1) Using the data from page 7 of this packet of notes, calculate the abundances of each of the two
isotopes of chlorine.
2) Thallium has two stable isotopes, 203Tl and 205Tl. What is the weighted average atomic weight of
thallium? Which isotope is more abundant? Explain
2.5 Atoms and the Mole (Counting by Weighing)
In chemistry we need a method of counting atoms, no matter how small they are. We must be able to
connect the macroscopic world (what we can see) with the microscopic world of atoms, molecules and
ions. We do this by defining a convenient unit of matter that contains a known number of particles. The
chemical counting quantity is the mole (mol). The mole is the SI base unit for measuring the amount of
a substance.
A mole is the amount of a substance that contains as many elementary entities (atoms, molecules, or
anything else) as there are atoms in exactly 12 g of the carbon-12 isotope
In 12.0 g of carbon-12 atoms there are 6.02 x 1023 atoms (this is Avogadro’s Number)
1
2.0 g carbon-12 atoms
= 6.02 x 1023 carbon atoms
= 1 mole
Avogadro’s Number
The Molar Mass
The mass in grams of one mole of atoms of any element (6.02 x 1023 atoms of that element) is the molar
mass of that element. The units for the molar mass of an element are grams/mole. For elements,
molar mass is an amount in grams numerically equal to the atomic mass in atomic mass units. This value is
most easily found on the periodic table:
13
Counting ATOMS By Weighing
Molar mass of copper (Cu) =
In other words…
mass of exactly mol of Cu atoms
=
63.546 g/mol
=
mass of 6.02 x 1023 Cu atoms
1 mole Cu
=
6.02 x 1023 atoms of Cu
29
Cu
63.546
= 63.546 g Cu
Practice:
1) a) What is the mass, in grams, of 1.5 mol of copper?
b) If a copper ornament has a mass of 2.0 g, how many copper atoms are in the ornament?
c) If a copper ornament has a mass of 2.0 g, how many moles of copper atoms are in the ornament?
d) What is the mass of a single atom of copper?
14
Homework
2) i) A lead fishing weight has a mass of ______g,
Conversion Table:
1 mole Pb atoms
=
______________g Pb a
a) How many moles of lead atoms are present?
=
6.02 x 1023 atoms of Pb
b) How many lead atoms are present?
c) What is the mass of one atom of lead in grams?
3) The mass of a single piece of pencil graphite (pure carbon) is ____________g.
Conversion Table:
1 mole C atoms
=
______________g C
a) How many moles of carbon atoms are present?
=
6.02 x 1023 atoms of C
b) How many carbon atoms are present?
c) If you wanted 6.5 x 1013 carbon atoms, how many grams of carbon would you need to mass out?
d) If you wanted 6.5 x 1013 carbon atoms, how many moles of carbon atoms would you need?
4) The mass of Mr. B’s gold ring (Au) is ____________g.
Conversion Table:
1 mole Au atoms
=
______________g Au
a) How many moles of gold atoms are present?
= 6.02 x 1023 atoms of Au
b) How many moles of gold atoms are present?
15
b) a) A single atom of this element has a mass of 2.28 x 10-22 g. What is its molar mass and identify the
element? (Hint: Remember the units for molar mass are g / mol)
c) To what group and period does the element in part a belong? Group_________Period_________
6) A 5.00 g sample of an unknown element is known to contain 0.2632 moles of atoms. What is the
identity of the unknown element (Hint: Remember the units for molar mass are g / mol)? What state of
matter is this element present in at room temperature?
7) a) Which has more atoms present 1 mole of Copper (Cu) or 1 mole of Carbon (C)? Explain
b) Which has a greater mass 1 mole of Copper (Cu) or 1 mole of Carbon (C)? Explain
c) Which contains more atoms 6.0 g of carbon or 10 g of neon? Explain
16
2.6 The Periodic Table
The most useful tool in chemistry is the ___________________ ___________________.
Some of the things we can get from it…
State of matter at room temperature:
Solid (Black), Liquid (Blue), Gaseous (RED)
Diatomic Elements (there are 7):
H2, N2, O2, F2, Cl2, Br2, I2
Information on Each of the elements:
29
________________
A. Features of the Periodic Table
Cu
_________________
63.546
_________________
______________
______________
Main Features of the Table
 Elements with similar chemical and physical properties lie in VERTICAL columns called _______ or
___________. The periodic table is made up of _______ groups. In the United States we see
them numbered 1A-8A and 1B-8B. Typically they are numbered 1-18.
 Groups 1-2 and 13-18 are called main group elements while the groups 3-12 are called transition
elements.
 There are ______ horizontal rows in the periodic table, these are called ______________
 Inner transition elements (Lanthanides and Actinides)
17
Element
Silver (Ag)
Calcium (Ca)
Iodine (I)
_________________
_________________
Period
_____
_____
_____
7
2
Group (Family)
___________
___________
___________
2
17
Main Group or Transition
___________________
___________________
___________________
___________________
___________________
Periodic Table Divided According to Element Properties
Metals
Properties: Metals are…
Solid at room temperature (except for mercury), conduct
electricity, ductile, malleable, form alloys (brass is a
homogeneous mixture of copper and zinc atoms), high luster
(shiny). Metals lie to the _____________________ of
the “staircase.”
**When reacting with non-metals atoms, metal atoms
tend to __________electrons to become stable forming
POSITIVELY charged atoms (______________).
Non-Metals
Properties: Non-Metals are…
Solid in some cases (ie. sulfur), liquid in some cases (ie. bromine), and gaseous in other cases (oxygen),
don’t conduct electricity. Nonmetals lie to the _____________________ of the “staircase.”
**When reacting with metals atoms, non-metal atoms tend to __________electrons to become
stable forming NEGATIVELY charged atoms (________________).
Metalloids (Semimetals):
Properties: Semimetals are…
elements that have characteristics of metals and non-metals. Nonmetals lie on the “staircase.”
B, Si, Ge, As, Sb, & Te
The Development of the Periodic Table
Mendeleev (Father of the Periodic Table)
The first periodic table of the elements created by Dmitri Mendeleev was arranged based on atomic
masses. Upon studying the chemical and physical properties of the elements known at his time (1869)
he realized elements with similar properties appeared in a regular pattern (periodicity). He organized
the elements into a table by lining them up in a horizontal row in order of increasing atomic mass.
Every time he came to an element similar to one already in the row, he started a new row. The columns
then contained elements with similar chemical and physical properties.
18
Moseley
In 1913, H.G.J Moseley REORDERED the table so that elements were organized into a table by
increasing atomic number. The law of chemical periodicity is now stated as “ the properties of the
elements are periodic functions of their _______________________________.
2.7 An Overview of the Elements
The groups of the periodic table have similar chemical and physical properties, and several of these
groups have distinct names that are important to know:
Group 1A (1) – The Alkali Metals
All elements are metals and solids at room
temperature. All metals in this group are VERY
reactive this means in nature you find these
elements in compounds. These elements react
with water to produce alkaline (basic) solutions.
Group 2A (2) – The Alkaline Earth Metals
All elements are metals and solids at room
temperature. All metals in this group are VERY
reactive this means in nature you find these
elements in compoundsThese elements (Except
Beryllium) react with water to produce alkaline
(basic) solutions.
19
Groups 1B-8B Transition Metals
All elements in this portion of the periodic table are metals
Virtually all transition metals have commercial uses.
Commercial Uses of Transition Metals:
Structural Material:
Iron (Fe), Titanium (Ti),
Paints:
Chromium (Cr), Copper (Cu)
Titanium (Ti), Chromium (Cr)
Catalytic Converters:
Platinum (Pl)
Coins:
Copper (Cu), Nickel (Ni), Zinc (Zn)
Nuclear Power Plants :
Uranium-235 (235U)
Biological Roles of Transition Metals:
Red Blood Cell –Iron (Fe) is found in the ___________ carrying
component of our blood (hemoglobin).
Group 3A (13)- Boron Group (Family)
Al, Ga, In, and Tl are all metals whereas Boron (B) is a metalloid
Aluminum (Al) is the most abundant metal in the earth’s crust
Group 4A (14) – Carbon Group (Family)
Starting in this group, groups will begin to contain more and more non-metals.
Nonmetals: Carbon Metalloids: Silicon, Germanium
Metals: Tin, Lead
Carbon is the basis for the great variety of compounds that make-up living things.
Carbon can exist in several distinct forms
Graphite
each with their own distinct set of
Diamond
chemical and physical properties
Bucky Ball Carbon
Buckminsterfullerene (BuckyBall Carbon)
Allotropes- Distinct forms of an element with their own unique physical and chemical properties
Group 5A (15) – Nitrogen Group (Family)
Nitrogen (N2) is the most abundant element in the Earth’s atmosphere. Nitrogen is also a critical
element found in chlorophyll, proteins, and DNA.
Phosphorous is essential to life as a constituent in bones and teeth.
20
Group 6A (16) – Oxygen Family
Oxygen (O2) is the second most abundant element in the Earth’s atmosphere. Most of the energy that
powers life on Earth is derived from reactions in which oxygen combines with other substances.
Example:
Burning Gasoline (Octane):
C8H18 (l) +
O2 (g)
 CO2 (g)
+
H2O (g)
Oxygen is the most abundant element in the Earth’s crust and in the human body
Oxygen also has allotropes: ____________________ and ____________________
Group 7A (17) – Halogens
All elements in this group are NON-METALS
This group contains the most reactive of all
NON-METAL elements
All elements in this group are diatomic elements
(F2, Cl2, Br2, and I2)
All react VIOLENTLY with alkali metals (also
with other metals just not as violently)
Group 8A (18) – Noble Gases
All elements in this group are NON-METALS
This group contains the least reactive of all NON-METAL elements
21
Elemental Make-up: Human Body
2.1
1.9
10.0
3.1
18.1
64.8
Oxygen
Carbon
Hydrogen
Nitrogen
Calcium
Other
Elemental Make-up: Earth's Crust
7.6
4.8
3.4
7.9
49.8
26.5
Oxygen
Silicon
Other
Aluminum
Iron
Calcium
Elemental Make-up: Earth's Atmosphere
7.9
26.5
7.6
49.8
Nitrogen
Oxygen
Carbon Dioxide
Argon and Others
22
Periodic Table Practice Problems :
1) Identify a Noble Gas with 54 protons in the nucleus
________
2) In what period(s) do we find a solid, liquid, and a gas element (at lab conditions)
________
3) In what group(s) do we find a solid, liquid, and a gas element (at lab conditions)
________
4) Identify a transition element with 42 electrons
________
5) How many elements are found in …
a) Period 2
b) Period 4
c) Group 15
________
________
________
6) In what group do we find 1 non-metal, 2 metalloid, and 3 metal elements
________
7) In what group do we find the most chemically reactive:
a) Metals
b) Non-metals
________
________
8) Which of the Noble gases has ONLY radioactive isotopes
________
9) This group containing only non-metals is made up of only monatomic gaseous
elements
________
10) A radioactive element whose atoms contain 95 protons and 95 electrons
that are commonly used in household smoke detectors.
________
11) A inner transition (actinide series) element whose atoms contain 90 protons
and 95 electrons that are commonly used treat lantern mantles to increase the
amount of light given off when they burn (this element is also radioactive)
________
12) The most reactive of all NON METAL elements
________
13) The most reactive of all METAL elements
________
14) What element has a molar mass that is ½ the molar mass of manganese (Mn)
________
15) Identify the element with the following symbol
39
??
19
16) An alkaline earth metal element that is important to healthy bones
17) A diatomic element found in group 17 period 5
________
________
________
23