ATOMS,
MOLECULES, AND
IONS
ARLAINE CHARISE GOLING-GOTOC, RMT, LPT
OBJECTIVES:
a. I will be able to describe and discuss the basic laws of
chemical change
b. I will be able to discuss how Dalton’s Atomic Theory could
explain the basic laws of chemical changes
c. I will be able to give the information provided by the atomic
number and mass number of an atom and its isotope
d. I will be able to differentiate atoms, molecules, and ions
e. I will be able to write the chemical formula of some molecules
f. I will be able to differentiate a molecular formula and an
empirical formula
g. I will be able to give the name of a compound, given its
chemical formula
KEYWORDS:
a. Law of Conservation of
Matter
b. Law of Definite
Proportion
c. Law of Multiple
Proportion
d. Dalton’s Atomic Theory
e. Atomic number
f. Mass number
g. Isotope
h. Atom
i. Molecule
j. Ion
k. Chemical formula
l. Molecular formula
m. Empirical formula
ONE VOLUNTEER STUDENT….
Cut a piece of paper into half…
into half …..
into half ….
into half ….
into half ….
into half ….
into half ….
Can you still go
cutting the paper into
half?
Atoms –
Building
Blocks of
Matter
The Atom: From Idea to Theory
Democritus
Greek Model
“To understand the very large,
we must understand the very small.”
Democritus’s model of atom
No protons, electrons, or neutrons
Solid and INDESTRUCTABLE
HOWEVER……
Beginning late 1800’s
LAWS OF CHEMICAL CHANGES
a. Law of Conservation of Mass
b. Law of Definite Proportion
c. Law of Multiple Proportion
LAW OF CONSERVATION OF MASS
In a chemical reaction, no change in
mass takes place. The total mass of
the products is equal to the total mass
of the reactant
Discovered by Antoine
Laurent Lavoisier (174394) about 1785.
Law of Conservation of Mass
Law of Conservation of Mass
Solve:
a. How many grams of water will be
formed if 1.00 g hydrogen gas reacts
with 8.00 g oxygen? The reaction can be
represented by the following word
equation:
hydrogen + oxygen
water
Solve:
c. Magnesium burns in air to form magnesium
oxide, as represented by the following word
equation:
magnesium + oxygen
magnesium oxide
When 2.43 g magnesium was burned, 4.03 g
magnesium oxide was produced. How many
grams of oxygen reacted with the magnesium?
Law of Definite Proportions
•
Substances always contained their
elements in the same proportions by
mass. For example: for any sample
of sodium chloride, the mass of the
sample is always 39.34% Na and
60.66% Cl.
Law of Multiple Proportions
If two elements can combine to form more
than one compound, the mass of one element
that will combine with a fixed mass of the other
element are in a ratio of small whole numbers.
Example:
When carbon which reacts with oxygen to
form carbon monoxide and carbon dioxide.
a. In carbon monoxide, 1.00 g carbon
combines with 1.33 g oxygen; whereas, in
carbon dioxide, 1.00 g carbon combines
with 2.66 g oxygen.
b. It can be seen that the ratio is 1:2.
Legos are Similar to Atoms
H
H2
H
H
O
+
H2
H
H
O2
H
O
H 2O
H
O
O
H
H 2O
Lego's can be taken apart and built into many different things.
Atoms can be rearranged into different substances.
JOHN DALTON
DALTON’S ATOMIC THEORY
1. All matter is composed of atoms.
2. Atoms of the same elements are exactly the
same and atoms of different elements are
different.
3. Atoms cannot be created, destroyed, or
subdivided.
4. Atoms of different elements combine in
whole number ratios to form compounds.
5. In chemical reactions, atoms are combined,
separated, or rearranged.
Dalton’s Symbols
John Dalton
1808
Which postulate explain the
following law?
a. Law of Conservation of
Mass
b. Law of Definite Proportion
c. Law of Multiple Proportion
Performance task
TIMELINE: Development of the atom (include
model, discoverer, description and any
information about the atom)
RUBRIC: Completeness – 20
Creativity - 20
On-time submission – 10
Total
50
IN A TABULAR FORM,
ENUMERATE THE 3
SUBATOMIC PARTICLES AND
DIFFERENTIATE THEM
ACCORDING TO THEIR
LOCATION, CHARGE AND
RELATIVE MASS
PARTICLE LOCATION
CHARGE
RELATIVE
MASS
PROTON
NUCLEUS
+
1
ELECTRON
OUTSIDE
NUCLEUS
-
0.0006
NEUTRON
NUCLEUS
+/-
1
What do you know about
the composition of
atoms in regards with
their atomic number and
mass number?
Counting Atoms
Reading the periodic table
11
atomic number
Na
symbol
22.990 average atomic mass (in amu’s)
Sodium name of element
23
mass number (the average atomic
mass rounded to the nearest whole number)
Atomic Number
the number of protons in the nucleus.
The atomic number identifies the
element!!!
Because atoms are neutral they
contain the same number of electrons
as protons.
(Therefore the atomic number is the
number of electrons as well.)
Mass Number
mass # = protons + neutrons
• always a whole number
• NOT on the Periodic Table!
Nuclear Symbol
Find the
number of protons
=9 +
number of neutrons
= 10
number of electrons
=9
Atomic number
=9
Mass number
= 19
19
9
F
Nuclear Symbol
Find the
= 11
number of protons
number of neutrons
= 12
number of electrons
= 10
Atomic number
= 11
Mass number
= 23
23
11
1+
Na
Sodium ion
Nuclear Symbol
Find the
= 11
number of protons
number of neutrons
= 12
number of electrons
= 10
Atomic number
= 11
Mass number
= 23
23
11
1+
Na
Sodium ion
Location of the subatomic particles
Neutron
Nucleus
e-
e-
+
Electrons
+
e-
+
+
+
+
Proton
Nucleus
e-
ee-
Carbon-12
Neutrons
Protons
Electrons
6
6
6
Activity: individual work
Answer it on your quiz
notebook…
Atomic # Mass # Protons Electrons Neutrons
4
14
9
28
8
9
12
11
52
24
19
20
Ions
– atoms that have lost or gained electrons are
called ions
Positive Ions (when an atom loses electrons)
Example:
23
Na
11 p+ and 11e-
11
Lose 1 electron
11p+ and 10e23
1+
Na
11
Ions
– atoms that have lost or gained electrons are
called ions
Negative Ions (when an atom gains electrons)
Example:
19
F
9 p+ and 9 e-
9
Gain 1 electron
9p+ and 10e19
1-
F
9
Isotopes
– atoms with the same number of protons
(atomic number is the same) but different
numbers of neutrons (mass number is
different). Usually isotopes are referred
to by their name (of symbol) and their
mass number. Every element on the chart
has at least 2 isotopes and some
elements have as many as 25 isotopes.
Example: The isotopes of hydrogen
have separate names rather than
being called hydrogen-1, hydrogen-2,
etc. Their names are protium (H-1),
deuterium (H-2), and tritium (H-3).
Isotopic Mass and Natural Abundance
WHAT ARE THE
DIFFERENCES OF ATOMS,
MOLECULES, AND IONS?
ACTIVITY…
Monoatomic ions are named
based on the element
a. For cations, the name of the element is
unchanged. If an element can form two ions
of different charges, the name, which is
usually derived from its Latin name, is
modified by the suffix –ic for the ion with the
higher charge, and –ous for that with the
lower charge.
b. For anions, the name of the element is
modified by the suffix –ide.
Name the following cations:
2+
Zn
a.
2+
b. Mg
+
c. K
2+
d. Pb
4+
e. Pb
Name the following cations:
2+
a. Zn - zinc ion
2+
b. Mg - magnesium ion
+
c. K - potassium ion
2+
d. Pb - plumbous ion or lead (II) ion
4+
e. Pb - plumbic ion or lead (IV) ion
Name the following anions:
a. Br
2b.S
2c. O
d. I
-
Name the following anions:
--
a. Br bromide ion
2b.S - sulfide ion
2c. O - oxide ion
d. I - iodide ion
Polyatomic anions are named based
on the atomic constituents and the
suffix – ide
The most common examples are:
a. OH – hydroxide ion
b. CN-– cyanide ion
OXYANIONS – polyatomic anions in
which a nonmetal is combined with an
oxygen
Rule 1 - named based on the root word of the
central (or non-oxygen) atom and the suffix –
ate for the one with more oxygen atoms and –
ite for the one with less oxygen atom.
a. NO3 – nitrate ion
b. NO2 - nitrite ion
OXYANIONS – polyatomic anions in
which a nonmetal is combined with
an oxygen
Rule 2 – the ion with least # of O2 takes
the prefix hypo (means less) together with
the suffix – ite, the next takes only the suffix
– ite, then the next takes the suffix – ate,
with the ion containing the highest # of O2
uses the prefix – per (meaning more)
together with the suffix – ate.
EXAMPLE:
ClO- - hypochlorite
ClO2- - chlorite
3ClO - chlorate
4ClO - perchlorate
CHEMICAL FORMULA
-
combination of symbols for atoms or
ions that are held together chemically.
a. O2 – oxygen gas
b. H2O – water
c. NaOH – sodium hydroxide (liquid Sosa)
d. HCl – hydrochloric acid (muriatic acid)
TWO TYPES OF CHEMICAL
FORMULA
MOLECULAR FORMULA
2. EMPIRICAL FORMULA
1.
TWO TYPES OF CHEMICAL
FORMULA
1. Molecular formula – gives the
composition of the molecule, in terms of the
actual number of atoms present. Examples
are the following:
i. C6H12O6
ii. K3PO4
iii. Na2C2O4
TWO TYPES OF CHEMICAL
FORMULA
2. Empirical formula – gives the composition of
the molecule, in terms of the smallest ratio of
the number of atoms present. Examples are the
following:
i. CH2O
ii. NaCO2
NAMING OF COMPOUNDS
Binary compounds – made
up of two elements.
2 TYPES OF BINARY COMPOUNDS
a. Ionic compounds – made up of a cation and
an anion. They are named by giving the name of
the cation first, followed by the name of the
anion.
i. NaI
ii. MgCl2
iii. FeS
iv. K2O
2 TYPES OF BINARY COMPOUNDS
b. Molecular compounds – made up of two
non-metals. They are named by giving the name
of the first nonmetal and then that of the second
nonmetal modified by the ending -ide. Molecular
compounds are usually gases.
i. HCl
ii. CO2
iii. SO3
NAMING OF COMPOUNDS
Ternary Compounds – made up of three
elements. The naming of ternary compounds
follows the same rule as that of the binary ionic
compound: the name of the cation is given first,
followed by the name of the anion.
i. NaNO3
ii. BaCrO4
iii. K2SO4
Acids – yield hydrogen
ions in aqueous
solutions.
Two types of Acids
Binary acids – composed of hydrogen and
another element, usually a nonmetal. The first
part of the name starts with the prefix hydrofollowed by the name of the element, modified
by the ending –ic. The second part consists of
the word ‘acid’. Name = hydro- (root name of
element) -ic + acid
i. HCl
ii. H2S
iii. HI
Two types of Acids
Ternary acids – made up of hydrogen and an anion,
usually containing oxygen. The first part of the name
consists of the root word of the name of the element,
modified by the ending –ic. The second part consists of
the word ‘acid’. If there is another acid with the same
atoms, the suffix –ous is used to denote the one with
less number of atoms. Name = (root name of element) ic (or –ous) + acid
i. HNO3
iv. H2SO3
ii. HNO2
v. H3PO4
iii. H2SO4
Writing Chemical Formulas
Oxidation number of an element – is a
positive or negative integer that is related
to the electronic structure of the atom.
- # of electrons that is approximately
lost or gained by an atom in a molecule
formation.
Steps in writing chemical formulas:
1.
2.
3.
Write the symbol of both positive and negative
ions. Indicate their respective oxidation numbers.
Criss-cross the oxidation numbers of the ions, to
be written as subscripts. This balances the
oxidation number of ions involved to an algebraic
sum of zero.
In the case of polyatomic ions, enclosed in
parentheses the ionic formula when the subscript
is greater than 1.
Write the formula of the
following compound:
i. Silver nitrate
ii. Potassium iodide
iii. Nitrogen dioxide
iv. Barium chloride
v. Hydrobromic acid