Unit 3 Test Review

Unit 3 Test Review

The test is tomorrow!

What will be on the test?

• Ions

• Ionic Bonds

• Writing formulas for Ionic Bonds (Criss Cross Method)

• Covalent Bonds

• Lewis Dot structures

Ions!

(Cations and Anions)

Multiple Select

(Check all that apply). Cations are...

• positive

• more protons than electrons

• metals

• nonmetals

Multiple Select

(Check all that apply) Anions are...

• negative

• more electrons than protons

• formed when a neutral atom gains electron(s)

• nonmetal

Ionic Bonds

Open Ended

What is an ionic bond?

An Ionic Bond is

• between a metal and nonmetal

• formed by the transfer of electrons

• the metal will transfer electrons to the nonmetal

• opposites attract!

Multiple Choice

Which of these compounds is an ionic compound?

• Cl₂

• HBr

• KF

• CO₂

Multiple Choice

Which of these is NOT an ionic compound?

• KBr

• MgS

• BeF₂

• N₂O

Writing Formulas for Ionic Compounds

Criss Cross Method!

Ionic compounds

• Net charge is 0

• Positives balance out negatives

• If the two charges don't cancel out, use criss cross method

Multiple Choice

Write the ionic formula for Ca and Br?

• Ca₂Br

• CaBr₂

• CaBr

• Ca₂Br₂

Multiple Choice

Write the ionic formula for Be and N

• Be₂N₃

• Be₃N₂

• Be₂N₂

• Be₃N₃

Covalent Bonds

Share electrons!

Covalent Bonds

Share electrons to satisfy the octet rule. One covalent bond is 2 shared electrons

Sometimes

• Single bonds

• Double bonds

• Triple bonds

• All to satisy the octet rule

Multiple Choice

Which of the following is NOT formed by a covalent bond?

• K₂S
• H₂O
• I₂
• CO₂

Multiple Choice

What two types of atoms make a covalent bond?

• 2 Nonmetals
• 1 Nonmetal and 1 Metal
• 2 Metals
• 2 Noble Gases

Multiple Choice

How do covalent bonds form?

• Donating & receiving valence e- between atoms.
• Opposite slight charges attract each other between compounds.
• Scientists are still not sure how they form.
• Sharing valence e- between atoms.

Electron Dot

Show the number of valenece electrons

Multiple Choice

This could be the dot diagram of

• Mg

• Cl

• C

• O

Multiple Choice

This is a correct dot diagram for neon (Ne)

• true

• false

Multiple Choice

How many dots would you put around carbon, a group 4A element?

• 4

• 6

• 8

• 18

Lewis Dot Structures

Last thing!

Steps

• Count and add up all valence electrons

• Pick the central atom

• Draw skeleton structure

• Add the remaining electrons in pairs until all the electrons have been used. Double or triple bonds might be used.

• Check that the octet rule is being satisfied for all elements (H & He are exceptions. They want 2)

Multiple Choice

What bond is formed between 2 or more nonmetals sharing electrons?

• Covalent bond

• Ionic bond

• Metallic bond

Multiple Choice

In HCN how many total valence electrons are there? (Hint: Step 1 of drawing a lewis dot structure)

• 14

• 18

• 10

• 4

Multiple Choice

Which of the following is the correct Lewis dot structure for the molecule fluorine (F₂)?

• A
• B
• C
• D

Multiple Choice

Which is the correct molecular structure for carbon dioxide CO₂?

Multiple Choice

What is the correct Lewis Dot Structure for ammonia NH₃