Review Part 4: The
Periodic Table
Chemistry
Spring 2011
Vocabulary: List 4
43.
44.
45.
46.
47.
reactant: starting material
consumed in a reaction
product: finishing material formed
in a reaction
mole: 6.02x1023 of anything
Avogadro’s number: 6.02x1023
molar mass: mass of one mole of a
substance
1
Vocabulary: List 4 cont.
48.
49.
50.
51.
52.
53.
kinetic molecular theory: molecules are
in constant random motion
pressure: caused by collisions of
molecules with container walls
temperature: average kinetic energy of
molecules
volume: space occupied
diffusion: spread of particles
STP: standard temperature and
pressure; 1 atm and 0º
0ºC
Periodic Table
Ordered by increasing atomic
number
2
Valence Electrons
Number of electrons in outermost
shell
Based on group # in PT
Octet Rule
Atoms want to
have 8 valence
electrons!!!
3
Gaining/Losing Electrons
If an atom gains electrons, it
becomes negatively charged.
• i.e.: O + 2e- O2-
If an atom loses electrons, it
becomes positively charged.
• i.e.: Al Al3+ + 3e-
How many lost or gained? So that it
follows octet rule
Charges of Groups
4
Combining Atoms
Atoms combine in ratios such that
positive and negative charges cancel
out
Example: What would the formula be
for a compound combining Li and S?
• Li is +1 (Li+). S is -2 (S2-).
• Need two Li+ to cancel out one S2• Formula is Li2S.
Periodic Trends: Ionization Energy
5
Periodic Trends: Electronegativity
***Exception: Noble gases have LOW electronegativity
Periodic Trends: Atomic Radius
6
Atomic Radii: Cations/Anions
Cations (+) have fewer e’s and are
smaller
Anions (-) have more e’s and are
bigger
Atomic Mass
Average value of the mass of an
element
i.e.: Chlorine has an atomic mass of
35.45 g/mol because there is mostly
chlorine-35 but also some chlorine37.
7
Calculating Molar Mass
Sum up the atomic masses of the
atoms making up a molecule.
Example: What is the molar mass of
C2HF3?
• molar
• molar
• molar
• molar
mass
mass
mass
mass
=
=
=
=
2 x m C + 1 x m H + 3 x mF
2 x 12 + 1 x 1 + 3 x 19
24 + 1 + 57
82 g/mol
Sample Question 1
A neutral atom contains 12 neutrons
and 11 electrons. The number of
protons in this atom is
A 1
B 11
C 12
D 23
8
Sample Question 2
What determines the order of
placement of the elements on the
modern periodic table?
A atomic number
B atomic mass
C the number of neutrons, only
D the number of neutrons and
protons
Sample Question 3
Which of the lists below has the
elements arranged in order of
increasing atomic mass?
A Cl, K, Ar
B Fe, Co, Ni
C Te, I, Xe
D Ne, F, Na
9
Sample Question 4
When a lithium atom forms an Li+ ion,
the lithium atom
A gains a proton
B gains an electron
C loses a proton
D loses an electron
Sample Question 5
What is the total number of electrons
in a Cr3+ ion?
A 18
B 21
C 24
D 27
10
Sample Question 6
Hydrogen has three isotopes with mass
numbers of 1, 2, and 3 and has an
average atomic mass of 1.00794 amu.
amu.
This information indicates that
A equal numbers of each isotope are
present
B more isotopes have an atomic mass of
2 or 3 than of 1
C more isotopes have an atomic mass of
1 than of 2 or 3
D isotopes have only an atomic mass of 1
Sample Question 7
An unknown element X can form a
compound with the formula XBr3. In
which group on the periodic table
would element X be found?
A 1
B 2
C 13
D 14
11
Sample Question 8
What occurs when an atom of chlorine forms
a chloride ion?
A The chlorine atom gains an electron,
and its radius becomes smaller.
B The chlorine atom gains an electron,
and its radius becomes larger.
C The chlorine atom loses an electron,
and its radius becomes smaller
D The chlorine atom loses an electron,
and its radius becomes larger.
Sample Question 9
Which list of elements from group 2 on
the periodic table is arranged in
order of increasing atomic radius?
A Be, Mg, Ca
B Ca, Mg, Be
C Ba, Ra, Sr
D Sr, Ra, Ba
12
Sample Question 10
The
A
B
C
D
molar mass of Ba(OH)2 is
154.3 g
155.3 g
171.3 g
308.6 g
13