BS0011_SEM1/LEC1/01

Question 1

What is an element?

Answer 1

Each of more than 100 substances
Cannot be chemically interconverted or broken down into smaller substances
Primary constituents of matter

Question 2

How are elements distinguished?

Answer 2

By atomic number
Which is the number of protons in nuclei of atom

Question 3

What is an atom?

Answer 3

Smallest particle of a chemical element that can exist

Question 4

What are molecules?

Question 5

What are compounds?

Question 6

Are all molecules compounds?

Question 7

What is valency?

Question 8

What is a valence shell?

Question 9

What’s meant by positive valency?

Question 10

How do you work out valency?

Question 11

Why do atoms join? (Gain, lose, share e-‘s)

Question 12

What does a valency number of 2 mean for Oxygen?

Question 13

What is an ionic bond?

Question 14

Describe the bonding between Sodium and Chlorine.

Question 15

What are covalent bonds?

Question 16

Describe the bonding in water.

Question 17

Describe the bonding in carbon dioxide.

Question 18

What is the structure of solid NaCl?

Question 19

Describe the structure of NaCl.

Question 20

What charge does an ionic compound have?

Question 21

Ionic bonds are __________ in __________, but ________ when placed in ___________ __________________.

Question 22

What happens to electrons in ionic bonds?

Question 23

What is an ionic compound?

Question 24

How do ionic bonds form?

Question 25

What is the result of a transfer of electrons?

Question 26

What holds ionic compounds together?

Question 27

What happens to electrons in a covalent bond?

Question 28

What happens to each hydrogen atom by sharing electrons in H2?

Answer 28

Both have a full valence shell.

Question 29

How is a covalent bond depicted and what does it show?

Answer 29

Straight line between 2 atoms Represents sharing of a pair of electrons

Question 30

What charge does a covalent compound have?

Answer 30

No charge

Question 31

What is a lone pair?

Question 32

What do lone pairs influence in terms of molecules?

Answer 32

Shapes of molecules

Question 33

How is a double bond formed?

Question 34

Compare double bonds to single bonds.

Question 35

Describe the covalent bonding between 2 oxygen atoms.

Question 36

Describe the structure of benzene or Aromatic compounds in general.

Question 37

Where are valence electrons in Benzene?

Answer 37

Free to move anywhere in delocalised ring

Question 38

What property allows larger molecules to be formed?

Question 39

Why can CH3COOH be formed?

Answer 39

Hydrogen has a valency of 1 Oxygen has a valency of 2 Carbon has a valency of 4 Each atom bonds to the same number of atoms as its number of valence electrons Valence electrons are shared to form a bond

Question 40

What is CH3COOH or C2H4O2?

Answer 40

Acetic acid

Question 41

What is dative coordinate bonding?

Question 42

Which atom must the electrons in a dative bond be given to?

Answer 42

An atom or ion with an empty orbital

Question 43

Describe the formation of an ammonium ion.

Answer 43

Nitrogen donates a pair of electrons to a Hydrogen ion, for it to gain a full outer electron orbital. A dative coordinate bond is formed.