June 19th, 2021
Chemistry Final Exam review
Units 1 & 2
1. Define the terms atomic radius, ionization energy, electron affinity, and electronegativity.
Then, describe the periodic trends that exist for each when going down a column and
across a period.
Atomic radius - An estimate of the size of an atom from its nucleus to its outer perimeter;
decreases from left to right across a period & increases when moving down a group.
Ionization energy - The amount of energy required to remove an electron from a
gaseous atom; increases from left to right across an element period & decreases down a
group.
Electron affinity - The amount of energy released when an electron is added to a
gaseous atom; decreases down a group & increases from left to right across periods.
Electronegativity - The property that determines the relative ability of an atom to attract
electrons from bonded pairs in a compound; generally increases as you move from left
to right across a period & decreases as you move down a group.
2. a) Drawing lewis diagrams
b) Why do ions form?
Elements that have only one or two electrons in the outer valence shell are more
reactive and must form an ion through a bond with another element in order to increase
its stability. Elements that have 7 (or less) electrons in the outer valence shell are less
reactive and will take electrons from the highly reactive elements forming ions.
3. Draw Lewis diagrams to represent both ionic and covalent bonds.
4. a) Be able to identify and describe why double or triple bonds form in elements and
compounds.
Double and triple bonds offer more stability to compounds. Each element wants to have
eight electrons in its outer valence shell so that it is no longer reactive. In order to do
this, the atoms of each element are going to pair up and share their unpaired electrons.
b) Be able to draw Lewis diagrams that represent these compounds or elements.
, June 19th, 2021
5. a) Using differences in electronegativity, differentiate between ionic, covalent and polar
covalent bonds.
Electronegativity Difference Character of Bond
< 0.5 Mostly nonpolar covalent
0.5 - 1.7 Mostly polar covalent
> 1.7 Mostly ionic
b) How electronegativity is calculated:
(**Electronegativity is found in the top right corner of elements on the periodic table. You
then subtract the smaller number from the bigger number and check the difference with
the electronegativity table**)
Example: Li + C 2.5 - 1.0 = 1.5
Li: 1.0 Therefore it is polar covalent
C: 2.5
6. Identify what type of bonds that metals and non-metals generally form when they
combine. Identify what type of bonds two nonmetals generally form when they combine.
Ionic compounds - metals combined with non-metals
Covalent compounds - two non-metals combined
7. Explain why metals on the ‘staircase’ may not always behave like other metals do when
forming bonds.
Metalloids lie along the staircase and cannot quite be classified as metals, or nonmetals.
Most metalloids have some physical properties of metals and some physical properties
of nonmetals. They fall between metals and nonmetals and their ability to conduct heat
and electricity. They are shiny like metals, but brittle like nonmetals.
8. a) What is the Law of Conservation of Matter?
Matter cannot be created or destroyed.
b) How does it relate to balancing equations?
Chemical reactions must be BALANCED so that the law of conservation of matter holds
true.
9. Identify families in the periodic table.
Chemistry Final Exam review
Units 1 & 2
1. Define the terms atomic radius, ionization energy, electron affinity, and electronegativity.
Then, describe the periodic trends that exist for each when going down a column and
across a period.
Atomic radius - An estimate of the size of an atom from its nucleus to its outer perimeter;
decreases from left to right across a period & increases when moving down a group.
Ionization energy - The amount of energy required to remove an electron from a
gaseous atom; increases from left to right across an element period & decreases down a
group.
Electron affinity - The amount of energy released when an electron is added to a
gaseous atom; decreases down a group & increases from left to right across periods.
Electronegativity - The property that determines the relative ability of an atom to attract
electrons from bonded pairs in a compound; generally increases as you move from left
to right across a period & decreases as you move down a group.
2. a) Drawing lewis diagrams
b) Why do ions form?
Elements that have only one or two electrons in the outer valence shell are more
reactive and must form an ion through a bond with another element in order to increase
its stability. Elements that have 7 (or less) electrons in the outer valence shell are less
reactive and will take electrons from the highly reactive elements forming ions.
3. Draw Lewis diagrams to represent both ionic and covalent bonds.
4. a) Be able to identify and describe why double or triple bonds form in elements and
compounds.
Double and triple bonds offer more stability to compounds. Each element wants to have
eight electrons in its outer valence shell so that it is no longer reactive. In order to do
this, the atoms of each element are going to pair up and share their unpaired electrons.
b) Be able to draw Lewis diagrams that represent these compounds or elements.
, June 19th, 2021
5. a) Using differences in electronegativity, differentiate between ionic, covalent and polar
covalent bonds.
Electronegativity Difference Character of Bond
< 0.5 Mostly nonpolar covalent
0.5 - 1.7 Mostly polar covalent
> 1.7 Mostly ionic
b) How electronegativity is calculated:
(**Electronegativity is found in the top right corner of elements on the periodic table. You
then subtract the smaller number from the bigger number and check the difference with
the electronegativity table**)
Example: Li + C 2.5 - 1.0 = 1.5
Li: 1.0 Therefore it is polar covalent
C: 2.5
6. Identify what type of bonds that metals and non-metals generally form when they
combine. Identify what type of bonds two nonmetals generally form when they combine.
Ionic compounds - metals combined with non-metals
Covalent compounds - two non-metals combined
7. Explain why metals on the ‘staircase’ may not always behave like other metals do when
forming bonds.
Metalloids lie along the staircase and cannot quite be classified as metals, or nonmetals.
Most metalloids have some physical properties of metals and some physical properties
of nonmetals. They fall between metals and nonmetals and their ability to conduct heat
and electricity. They are shiny like metals, but brittle like nonmetals.
8. a) What is the Law of Conservation of Matter?
Matter cannot be created or destroyed.
b) How does it relate to balancing equations?
Chemical reactions must be BALANCED so that the law of conservation of matter holds
true.
9. Identify families in the periodic table.
