Science Ionic & Molecular Compounds

Question 1

What is a compound?

Answer 1

• Compounds are pure substances.
• They are made up of chemical combinations of the elements.

Question 2

What are molecular compounds?

Answer 2

• They are made of non-metals.
• They stay together by sharing electrons in their valence shells. Held together by covalent bonds (always pairs of electrons)
  Ex: H2O, CH4, etc.

Question 3

What is a “stable octet”?

Answer 3

• It means an atom wants to have 8 electrons in its valence shell.
• The only atom that will be stable with 2 electrons in its valence shell is hydrogen.

Question 4

What are diatomic molecules?

Answer 4

Diatomic molecules are molecules that contain only two atoms bonded to one another.
Seven diatomic elements: HOFBrINCl the clown.

Question 5

What are the hydrocarbons?

Answer 5

They are compounds that only have carbon and hydrogen atoms.
Ex.
- CH4: Methane
- C2H4: Ethene
- C3H8: Propane

Question 6

The diagrams for Molecular Compounds (3):

Answer 6

• Bohr-Rutherford (Solar System)
• Model Diagram (One spring = one covalent bond)
• Stick Diagram (One bond = one hyphen. Ex: Cl2 = Cl–Cl)

Question 7

Name 5 compounds:

Answer 7

• H2O: Water
• CH4: Methane
• NH3: Ammonia
• CO2: Carbon Dioxide
• H2O2: Hydrogen Peroxide

Question 8

What are ions?

Answer 8

A particle with a charge. They can be positive or negative.
- Cation: Positive (+)
- Anion: Negative (-)
- They have full valence shells.

Question 9

Metal Elements:

Answer 9

• Groups #1, 2, 13.
• Have < 4 Valence Electrons.
• They give these Valence Electrons away.
• They are all positively charged.
  Ex: Be2+

Question 10

Non-Metal Elements:

Answer 10

• Groups # 15, 16, 17
• Have > 4 Valence Electrons.
• They pick up enough electrons to fill their valence shells.
• They now have a negative charge.
  Ex: F1-

Question 11

Where do you put the charge of an ion?

Answer 11

It is written as an exponent. (Negative/Positive)

Question 12

What are Ionic Compounds?

Answer 12

• Metal + Non-Metal
• Neutral (Total positive charge equals total negative charge)
  + create another ion if valence electrons cannot be properly distributed.

Question 13

What is the difference between Molecular and Ionic Compounds?

Answer 13

Molecular:
- Non-Metal + Non-Metal
- Connected by Covalent bonds
- Poor conductors of electricity
- Solid, Liquid, or Gas
- Made of atoms
Ionic:
- Non-metal + Metal
- Connected by Ionic Bonds
- Conducts electricity
- Solid
- Made of ions

Question 14

What is a covalent bond?

Answer 14

A covalent bond is a bond formed between two non-metal atoms sharing electrons.

Question 15

The diagrams for Ionic Compounds:

Answer 15

• Bohr-Rutherford (giving/taking away electrons)
• Electron Dot Diagram: In square brackets, charges outside, negative ions have 8 dots surrounding the element.

Question 16

How do atoms become ions?

Answer 16

Atoms become Ions by either giving up or taking electrons.

Question 17

Electrical Law:

Answer 17

Two ions are attracted to each other because of the electrical law: opposite charges attract.

Question 18

Why don’t group #18 elements make ionic compounds?

Answer 18

Group #18 elements do not make ionic compounds because their valence shells are full. (He= 2, everything else = 8)