Chemistry Term 1 Knowledge

Question 1

What is an atom?

Answer 1

The smallest unit of matter, contains sub-atomic particles such as electrons (- charge), protons (+ charge) and neutrons (0 charge).

Question 2

What are ions and what are their types?

Answer 2

Ions - charged atoms
Cations - positive charged atoms
Anions - negative charged atoms

Question 3

What is mass number?

Answer 3

Represented by A, the atomic mass is the amount of matter in the atom, equal to the number of protons + neutrons.

Question 4

What is atomic number?

Answer 4

Represented by Z, it symbolises the number of protons in the nucleus of atom.

Question 5

What are isotopes?

Answer 5

Atoms of the same element and same number of protons that have different number of neutrons to protons which make them radioactive, also known as radioisotopes.

Question 6

What is a molecule?

Answer 6

Two atoms of the same/different elements bonded together.

Question 7

What is electrostatic attraction?

Answer 7

A non-contact force attracting positive subatomic particles to negative ones.

Question 8

What are the periods and groups.

Answer 8

There are 7 periods in the periodic table that go horizontally and 8/18 groups that go vertically.

Question 9

What are the specific types of elements?

Answer 9

Alkali metals
Alkaline earth metals
Transitional metals
Halogens
Noble gases
Rare earth metals

Question 10

What are Isotopes?

Answer 10

Atoms of the same element that have the same number of protons but different number of neutrons.

Question 11

Stoichiometry

Answer 11

Branch of chemistry which utilised relationships between products and/or reactants in a chemical reaction to determine desired quantitative data.

Question 12

How do you convert grams of substance A to grams of Substance B?

Answer 12

Grams A => mol A => mol B => grams B

Question 13

How do you convert moles of substance A to moles of Substance B?

Answer 13

Moles A => Moles B

Question 14

Law of conservation of mass

Answer 14

In a chemical reaction, mass can neither be created nor destroyed.

Question 15

Types of reactions.

Answer 15

1. Combination or synthesis.
2. Decomposition
3. Single replacement/displacement
4. Double replacement/displacement
5. Combustion
6. Precipitation
7. Neutralisation (acid/base)

Question 16

Combination reaction

Answer 16

Reaction where 2 or more reactants combine to form a single product (which must be compound)

Question 17

Decomposition/decombination

Answer 17

Single reactant breaks down into multiple products.

Question 18

Single replacement/displacement

Answer 18

One element in compound is replaced by another element.

Question 19

Double displacement/replacement

Answer 19

Cations and anions swap partners to form compounds.

Question 20

Neutralisation

Answer 20

Reaction between acid and base and always produces salt and water and sometimes gas.

Question 21

Combustion

Answer 21

Reaction where O2 reacts with reactants and/or it produces H2O and CO2. General FORMULA: CyHx + O2 = CO2 + H2O

Question 22

Precipitation

Answer 22

Double replacement reaction where one of new substances is insoluble, which is a solid also known as precipitate). GENERAL FORMULA: AB(aq) + CD(aq) => AD(s) + CB(aq)

Question 23

What are the diatomic elements?

Answer 23

1. Bromine (Br)
2. Iodine (I)
3. Nitrogen (N)
4. Chlorine (Cl)
5. Hydrogen (H)
6. Oxygen (O)
7. Fluorine (F)

Question 24

Oxidation rules

Answer 24

• Element by itself has ON of 0
• Group 1A has always a +1
• Group 2A has always a +2
• Halogens usually have -1 but have a positive ON when with oxygen.
• Sum of ON’s for neutral compound =0
• Sum of ON’s for a polyatomic ion = Ionic charge of ion
• monoatomic ion has ON=ionic charge
• Oxygen is usually -2 but -1 in peroxide

Question 25

General formula for peroxides

Answer 25

A2O2, with A representing a metal or a non-metal.

Question 26

Indications that a compound is a peroxide

Answer 26

If it contain 2 oxygen atoms.

Question 27

Electronegativity

Answer 27

The measure of an atoms ability to attract electrons towards itself when it forms a chemical bond.