Chemical Bonding

Question 1

What is a compound?

Answer 1

A substance that is made from two or more different elements combined together chemically.

Question 2

What is the octet rule?

Answer 2

When bonding occurs, atoms tend to reach an electron arrangement with eight electrons in their outermost energy level.

Question 3

What is an ion?

Answer 3

Charged atom or group of atoms.

Question 4

What is an ionic bond?

Answer 4

The force of attraction between oppositely charged ions in a compound. Ionic bonds are always formed by the complete transfer of electrons from one atom to another.

Question 5

What is the hydroxide ion?

Answer 5

OH-

Question 6

What is the Nitrate ion?

Answer 6

NO3-

Question 7

What is the hydrogencarbonate ion

Answer 7

HCO3-

Question 8

What is the permanganate ion?

Answer 8

MnO4-

Question 9

Carbonate ion

Answer 9

CO3–

Question 10

Chromate ion

Answer 10

CrO4–

Question 11

Dichromate ion

Answer 11

Cr2O7–

Question 12

Sulfate ion

Answer 12

SO4–

Question 13

Sulfite ion

Answer 13

SO3–

Question 14

Thiosulfate ion

Answer 14

S2O3–

Question 15

Phosphate ion

Answer 15

PO4—

Question 16

Ammonium ion

Answer 16

NH4+

Question 17

What are the characteristics of transition metals?

Answer 17

1. They have variable valency
2. Usually form coloured compounds
3. Widely used as catalysts.

Question 18

What are transition metals?

Answer 18

One that forms at least one ion with a partially filled sublevel

Question 19

What are molecules?

Answer 19

A group of atoms joined together. It is the smallest particle of an element or compound that can exist independently.

Question 20

What is valency?

Answer 20

Valency of an element is defined as the number of atoms of hydrogen or any other monovalent element with which each atom of the element combines.

Question 21

What is a sigma bond?

Answer 21

Formed by the head on overlap of two orbitals, single bonds are always sigma bonds.

Question 22

What is a pi bond?

Answer 22

Formed by the sideways overlap of p orbitals.

Question 23

Single, double and triple bonds

Answer 23

Single bonds are always sigma bonds, double bonds are always 1 sigma and 1 pi bonds and triple bonds are always 1 sigma bond and 2 pi bonds

Question 24

What are the properties of ionic compounds?

Answer 24

1. Contain a network of ions in the crystal
2. Usually hard and brittle
3. Have high melting points and boiling points
4. Usually solid at room temperature
5. Conduct electricity in molten state or when dissolved in water.

Question 25

What are the properties of Covalent Compounds?

Answer 25

1. Contain individual molecules 2. Usually soft 3. Have low melting and boiling points 4. Usually liquids, gases or soft solids at room temperature. 5. Do not conduct electricity

Question 26

What does VSEPR stand for?

Answer 26

Valence Shell Electron Pair Repulsion Theory

Question 27

What is VSEPR?

Answer 27

This theory states that the shape of a molecule depends on the number of pairs of electrons around the central atom. Lone pair/Lone pair>bond pair/lone pair>bond pair/bond pair.

Question 28

What is Electronegativity?

Answer 28

The relative attraction that an atom in a molecule has for a shared pair of electrons in a covalent bond.

Question 29

What is a polar covalent bond?

Answer 29

A bond in which there is unequal sharing of the pair(or pairs) of electrons. This causes one end of the bond to be slightly positive(S+) and the other end slightly negative(S-)

Question 30

What is pure covalent?

Answer 30

A covalent bond where there is an equal sharing of the two electrons in the bond.

Question 31

What are the main uses of electronegativity values?

Answer 31

1. To predict the polarity of covalent bonds 2. To predict which compounds are ionic and which are covalent.

Question 32

Polarity

Answer 32

0-0.3 - Non polar 0.3-1.7 - Polar covalent 0.3 - 1.0 - Polar covalent 1.0 - 1.7 - Highly polar covalent Greater than or equal to 1.7 - Ionic bond

Question 33

Why are there some molecules, which even though they are polar covalent, are non polar?

Answer 33

Since the centre of the partial negative charges coincides with that of the partial positive charges, non of these molecules are polar.

Question 34

What molecules are non polar even though they are polar?

Answer 34

BCl3, CO2, CCl4

Question 35

What is intramolecular bonding?

Answer 35

Bonding within or inside molecules. (Ionic, Covalent)

Question 36

What is intermolecular bonding?

Answer 36

Bonding that takes place between molecules( Van Der Waal, dipole-dipole, hydrogen bonding)

Question 37

What are Van Der Waal Forces?

Answer 37

Weak attractive forces between molecules resulting from the formation of temporary dipoles. They are the only forces of attraction between non-polar molecules. The bigger the molecule the stronger the Van Der Waal force, this means a higher boiling point.l

Question 38

What are dipole-dipole forces?

Answer 38

Forces of attraction between the negative pole of one polar molecule and the positive pole of another molecule.

Question 39

What are hydrogen bonds?

Answer 39

Particular types of dipole-dipole attractions between molecules in which hydrogen atoms are bonded to nitrogen, oxygen or fluorine. The hydrogen atom carries a partial positive charge and is attracted to the electronegative atom in another molecule. Thus, the hydrogen bond acts as a bridge between two electronegative atoms in separate molecules. Stronger than Van Der Waal and dipole-dipole but weaker than covalent.