Chemistry Semester Review

Semester Exam Review

Pre AP Chemistry 2022-2023

​December 5, 2022

The Chemistry Semester Exam is TOMORROW, TUESDAY! Try to review as much as you can :)

​Periodic Table trends

​How to calculate molar mass?

Subject | Subject

Some text here about the topic of discussion

1.Identify the elements

2. Count how many atoms of each element.

3.Find the atomic mass in the periodic table.

4.Multiply it and then add each mass.

Multiple Choice

What is the molar mass of NF₃?

• 33.01 g/mol

• 61.03 g/mol

• 71.01 g/mol

• 99.03 g/mol

​Percent Composition

• You need to remember the formula and steps to calculate percent composition in the next slide question.

Match

The percent composition of Mg and O in MgO? Remember you need to first calculate the molar mass of MgO. Then use the formula.

• Mg

• O

• Molar Mass of MgO

60%

40%

40.30 gr/mol

• 60%

• 40%

• 40.30 gr/mol

How to calculate Formal Charge?

Some text here about the topic of discussion

​You need to remember the formula for formal charge to answer the next question.

Match

Calculate the formal charge of each atom represented in the molecule in the picture. (Look for the Formal charge formula from previous slide.)

• H

• N

• C (between hydrogens)

• C (between O's)

• O (with double bond)

0

+1

0

0

0

• 0

• +1

• 0

• 0

• 0

VSEPR Formula

Multiple Choice

The VSEPR Formula that best represents this molecule...₃

• AB₃E

• AB₂E

• AB₂E₃

• A₃B₂E

​Molecular & Electron Geometry

In order for you to determine the electron or molecular geometry of a molecule. You will have access to the table. It is very helpful to be able to know the ABE (VSEPR formula) of the molecule to correctly identify the type of shape.

Fill in the Blank

The electron geometry of the molecule is ...

Fill in the Blank

The MOLECULAR geometry (shape) of the molecule is ...

​Structural Isomers

Isomers in which atoms are completely arranged in a different order with the same molecular formula.

Same formula, but different order of atoms.

Multiple Choice

Which formulas represent compounds that are isomers of each other?

Multiple Choice

Are the compounds shown isomers

• Yes

• No

​Polarity of molecules

Covalent bonds are divided into polar and non polar bonds.

Polar bonds

• Asymmetrical

• The branches might not match (atoms connected to central atom are not all the same)

• There will be lone pairs (dots) on the central atom

Nonpolar bonds

• Symmetrical

• The branches will match (atoms connected to central atom are the same)

• There will be lone pairs (dots) on the central atom

• There will be no lone pairs on central atom.

Multiple Choice

Classify the following molecule.

• polar

• nonpolar

Multiple Choice

Is the following molecule polar or nonpolar?

• polar

• nonpolar

Multiple Choice

Is this molecule polar or non-polar?

• Polar

• Non-polar

Multiple Choice

Is this molecule polar or non-polar?

• Non-polar

• Polar

Dimensional analysis

​Write and analyze the example problem below to answer the problem in the next slide. Remember that the units are the most important to set up correctly to get the correct result.

Multiple Choice

A 270.27 g sample of glucose C₆H₁₂O₆ is measured in the laboratory. How many molecules of glucose are in

the sample? Assume molar mass of glucose is 180.18 g/mol. If you want to get this right in your exam, please make sure you get a piece of paper and try to work out the problem. 10²³

• 6.02 x 10²³ molecules of C₆H₁₂O₆

• 9.03 x 10²³ molecules of C₆H₁₂O6

• 1.20 x 10²⁴ molecules of C₆H₁₂O₆

• 4.01 x 10²³ molecules of C₆H₁₂O₆

Multiple Choice

An Ionic Compound is formed between what two types of elements?

• Metal and Metal

• Metal and Nonmetal

• Nonmetal and Nonmetal

• Metal and Metalloid

Multiple Choice

In an Ionic Bond Valence Electrons are what?

• created

• destroyed

• gained or lost = transferred

• shared

Multiple Choice

Compounds held together with these bonds are malleable with high thermal and electrical conductivity due to freely moving electrons.

• Ionic Bond

• Metallic Bond

Multiple Choice

Occurs when cations are fixed within a sea of shared delocalized electrons...

• Ionic Bond

• Metallic Bond

Multiple Choice

Form a crystal lattice based on electrostatic attraction and repulsion in repeating patterns...

• Ionic Bond

• Metallic Bond

Multiple Choice

How do the following two elements bond together?
K¹⁺  S^2- 

• KS

• K₈S

• K₆S₃

• K₂S

Multiple Choice

Identify the following compound as ionic or covalent: SO₂

• ionic

• covalent

Multiple Choice

Which Lewis Dot Structure  is correct for the particular element?

Multiple Choice

What is the correct Lewis Dot Structure for ammonia NH3

Multiple Choice

Classify the following molecule.

• polar

• nonpolar

Multiple Choice

What type of bond is illustrated above?

• Covalent

• Metallic

• Ionic

• Oxygen

Multiple Choice

A bond between a nonmetal and a nonmetal is called a(n)

• covalent bond

• ionic bond

• metallic bond

• transfer bond

Multiple Choice

Identify the following compound as metallic, ionic or covalent: SO₂

• ionic

• covalent

• metallic

Multiple Choice

Cations

• Gain electrons, has an overall positive charge

• Lose electrons, has an overall positive charge

• Lose electrons, has an overall negative charge

• Gain electrons, has an overall negative charge

Multiple Choice

How many Aluminum atoms are in Al₂O₃?

• 3

• 5

• 2

• 1

Multiple Choice

An ion with a negative charge is called...

• Anion

• Cation

Multiple Choice

How do the following two elements bond together?
Na¹⁺  F^1-         

• NaF

• NaF₃

• Na₃F

• Na₁F₂

Multiple Choice

What would be the proper chemical formula for combining Al³⁺ and Cl^- :

• AlCl₃

• Al₃Cl

• AlCl

• Al₃Cl₃

Multiple Choice

As you move down a group, atomic radius increases because - 

• you add more and more neutrons

• you add more and more protons

• you add more and more shells (energy levels)

• you add more atomic mass

Multiple Choice

Francium (Fr) has the lowest ionization energy in Group 1 because -

• it has the smallest number of valence electrons

• it has the greatest atomic mass

• it has the greatest number of protons, so it attracts its electrons the strongest

• its 1 valence electron is very far from the nucleus with a lot of shielding from the nucleus, so little energy is needed to remove it

Multiple Choice

Which of the following will have a lower ionization energy than Scandium (Sc)?

• Helium (He)

• Titanium (Ti)

• Calcium (Ca)

• Magnesium (Mg)

Multiple Choice

Electronegativity is...

• the ability of an atom to attract/ accept electrons

• the ability of an atom to lose electrons

• the energy required to remove an electron from a specific atom

• how easy it is to make friends. 

Multiple Choice

As you move across the periodic table atoms tend to get smaller because, ______________.

• the atoms have more mass.

• the atoms have less mass

• the atoms have more protons.

• the atoms have less electrons.

Multiple Choice

Elements in the same column of the periodic table always have the same # of _______ as one another.

• Protons

• Neutrons

• Electrons

• Valence Electrons

Multiple Choice

The graph above shows the ionization energy values as the elements are arranged on the periodic table. Which conclusion cannot be drawn from the graph?

• The ionization energy drops significantly as you move down a group because the valence electrons are in a shell further from the nucleus.

• The ionization energy increases gradually as you move right across a period because the valence electrons are in a shell further from the nucleus.

• The ionization energy increases gradually as you move right across a period because you are adding more protons.

• The ionization energy increases when the valence electrons are more attracted to the nucleus.

Multiple Choice

Ionization energy is...

• the energy required to add an electron to a specific atom

• how much energy it takes to remove an electron from an atom

• the energy required to shield the outer electrons from the nucleus

• a measure of the ability of an atom to attract electrons

Multiple Choice

Ionization energy __________ down a column and ________ to the right.

• decreases, increases

• increases, decreases

• increases, increases

• decreases, decreases

Multiple Choice

Which atoms has the HIGHEST first ionization energy?

• He

• Ar

• Xe

• Rn