ESCS Final Exam Fall Study Guide
KEY
1. What do we call a pure substance made of one type of atom that can NOT be broken down?
An element
A mixture contains the elements sulfur and iron.
Sulfur
Iron
Not Soluble in water
Not soluble in water
Solid Yellow powder smells like
rotten eggs
Boils at 444.674 º C
Solid Dark metal that is
magnetic
Boils at 2750 º C.
2. Using the physical properties in the chart, how would it be easiest to separate the mixture of sulfur and
iron?
Use a magnet to separate out the iron
3. What is the difference between a heterogeneous and homogeneous mixture?
Homogeneous is uniform throughout; heterogeneous is “lumpy” or inconsistent
4. What do we call the ability of one substance to dissolve in another substance?
Solubility
5. What does the Kinetic Theory state?
All particles of matter in constant motion.
6. What must have happened if a chemical change has occurred?
New substance has been formed.
7. What factors affect the pressure of an enclosed gas? Temperature, Volume, & # of Particles
8. What can be learned about an atom from the following:
a.
Its atomic number:
how many protons, and in neutral state how many electrons
b.
Its mass number:
sum of protons plus neutrons; weighted average of isotope mass
9. What electrical charges do protons, neutrons, and electrons have and where can each be found?
Proton is positive; neutron is neutral; electron is negative; proton & neutron are in nucleus;
electrons are outside the nucleus
10. What is an isotope? Same number of protons, different number of neutrons
11. What causes an electron to jump to a new energy level?
12. Why do atoms lose or gain electrons?
Atom gains or loses energy
To become more stable (octet rule)
13. How many valence electrons are in each group (family) of the periodic table?
Group 1/1A has 1; group 13/3A has 3, etc.)
14. Be able to define and give examples of the following:
Tied to group # (e.g.
a.
Alkali Metals Group 1
c.
Halogens
Group 17
b.
Alkaline Earth Metals Group 2
d.
Noble Gases Group 18
15.
e.
Transition Metals Groups 3-12
f.
Metals everything left & below
staircase (except H)
g.
Nonmetals everything right &
List some of the properties and characteristics of metals:
above staircase
h.
Metalloids on and immediately
below staircase
conductors, malleable, ductile,
solids at room temp
16.
List some of the properties and characteristics of nonmetals: insulators, brittle
17.
What kinds of elements share some of the properties of both metals and nonmetals? metalloids
18.
What are ions, cations and anions? Ions: any electrical charge; cations: positive; anions: negative
19.
How many valence electrons do the most reactive elements tend to have? One or seven
20.
What is the difference between an ionic bond and a covalent bond? Ionic transfers electrons;
covalent shares
21.
Which kinds of elements typically combine in such a way that electrons are transferred? Metals to
nonmetals
22.
Which kinds of elements typically combine in such a way that electrons are shared? Nonmetals with
nonmetals
23.
24.
25.
26.
Which kinds of elements typically form cations? Why and how? Metals; octet rule; give up
electrons to get to zero in valence shell Which kinds of elements typically form anions? Why and how? Nonmetals; octet rule; borrow
electrons to get full valence shell (eight)
When electrons are transferred, which elements do the “giving” and which do the “taking”?
Metals (with few valence electrons) give (lend) and nonmetals (with many electrons) take
(borrow).
Know what happens when an element becomes an ion.
a. When potassium becomes an ion, it: gives up an electron becomes a cation (with 1+ charge)
b. When nitrogen becomes an ion, it: borrows 3 electrons and becomes an anion (with 3- charge)
27.
Be able to determine the number of atoms that must be combined with another atom to form a
stable compound. For example:
a. Write the formula for how lithium atoms combine with oxygen atoms to make lithium oxide.
Li gives up e- and becomes Li+ cation; O takes on 2 e- and becomes O2- anion; criss cross for
Li2O
b. Write the formula for how beryllium atoms and chlorine atoms combine to make beryllium
chloride.
Be gives up 2 e- and becomes Be2+ cation; Cl takes on 1 e- and becomes Cl- anion; criss cross
for BeCl2
28. Know how to draw Bohr models and Lewis dot models for elements 1 – 20 on the periodic table.
a. Li
Bohr: ‘Li’ center; 1st shell 2 e-; 2nd shell 1
eLewis: ‘Li’ center and 1 dot
b. Mg
Bohr: ‘Mg’ center; 1st shell 2 e-; 2nd shell
8 e-; 3rd shell 2 e-; Lewis: ‘Mg’ center
and 2 dots
c. B
Bohr: ‘B’ center; 1st shell 2 e-; 2nd shell 3
eLewis: ‘B’ center and 3 dots
d. C
Bohr: ‘C’ center; 1st shell 2 e-; 2nd shell 4
eLewis: ‘C’ center and 4 dots
1 / 1A
H
2.1
Li
1.0
Na
0.9
K
0.8
Rb
0.8
Cs
0.8
e. P
Bohr: ‘P’ center; 1st shell 2 e-; 2nd shell 8
e-; 3rd shell 5 e-; Lewis: ‘P’ center and 5
dots
f. O
Bohr: ‘O’ center; 1st shell 2 e-; 2nd shell 6
eLewis: ‘O’ center and 6 dots
g. Cl
Bohr: ‘Cl’ center; 1st shell 2 e-; 2nd shell
8 e-; 3rd shell 7 e-; Lewis: ‘Cl’ center and
7 dots
h. Ne
Bohr: ‘Ne’ center; 1st shell 2 e-; 2nd shell
8 eLewis: ‘Ne’ center and 8 dots
Electronegativity
2 / 2A
Be
1.6
Mg
1.3
Ca
1.3
Groups
3 - 12
13 / 3A
B
2.0
Al
1.6
14 / 4A
C
2.5
Si
1.9
15 / 5A
N
3.0
P
2.2
16 / 6A
O
3.5
S
2.5
Keeping in mind, if the electronegativity difference is::
-less than or equal to 0.5 the bond is nonpolar covalent
-between 0.5 and 2.0 the bond is considered polar covalent
-greater than or equal to 2.0 the bond is ionic
29. Predict what kind of bond will form between the following:
a.
Lithium and fluorine (4.0 – 1.0 = 3.0) Ionic
b.
Carbon and Oxygen (3.5 – 2.5 = 1.0) Polar Covalent
17 / 7A
F
4.0
Cl
3.0
Br
2.8
I
2.7
18 / 8A
He
Ne
Ar
Kr
Xe
-
c.
Fluorine and Fluorine (4.0 – 4.0 = 0.0) Nonpolar Covalent
d.
Carbon and Hydrogen (2.5 – 2.1 = 0.4) Nonpolar Covalent
30. Which elements typically form a positive charge when bonding? Metals
31. Which elements are least likely to undergo bonding? Noble Gases (already have full shell)
32. How do the following atoms achieve a completely filled outer shell of electrons when they form ionic
bonds? What valence or oxidation number does each of these have?
a. Lithium
Loses 1 e-; valence 1+
b. Beryllium
Loses 2 e-; valence 2+
c. Boron
Loses 3 e-; valence 3+
d. Carbon
Loses 4 e-; valence 4+
e. Nitrogen
Gains 3 e-; valence 3f. Oxygen
Gains 2 e-; valence 2g. Fluorine
Gains 1 e-; valence 1h. Neon
Full shell – no change
33. Write the valence or oxidation number for each of the following elements or ions, and then use the criss
cross method to write the chemical formula for combining them into compounds:
a. Sodium and oxygen
Na+ and O2- 
Na2O
b. Beryllium and chlorine
Be2+ and Cl- 
BeCl2
c. Aluminum and Sulfur
Al3+ and S2-  Al2S3
d. Magnesium and Chlorine
Mg2+ and Cl- 
MgCl2
34. Use Lewis dot structures to decide how many electrons are shared by the atoms in each of the following
diatomic molecules; identify each of these as a single, double, or triple covalent bond:
a. F2
F – F each F has 7 dots & 1 shared
pair
Single covalent bond
b. Cl2
Cl – Cl
each Cl has 7 dots & 1
shared pair
Single covalent bond
35. What does a chemical formula represent?
c. O2
O = O each O has 6 dots & 2 shared
pairs
Double covalent bond
d. N2
N = N each N has 5 dots & 3 shared
pairs
Triple covalent bond
Number or ratio of atoms in compound