Principles of Chemistry

Question 1

Solids

Answer 1

• Fixed arrangement
• Vibrate about a fixed position
• Particles are tightly packed together

Question 2

Liquids

Answer 2

• Particles are randomly arranged
• Close together but slightly spaced apart
• Particles slide over each other

Question 3

Gases

Answer 3

• They are arranged randomly
• Spaced further apart
• Move quickly in all directions

Question 4

Solute

Answer 4

A solid which dissolves in a solvent

Question 5

Solvent

Answer 5

A liquid which a solute dissolves in

Question 6

Solution

Answer 6

A mixture of a solvent and solute

Question 7

Saturated solution

Answer 7

A solution in which no more solute can dissolve

Question 8

What is solubility

Answer 8

Mass of solute needed to dissolve in 100g of a solvent

Question 9

What is an element, compound and mixture

Answer 9

• Element contains only 1 type of atom
• Compounds are 2 or more elements chemically combined
• Mixture contains 2 or more elements not chemically combined

Question 10

What an atom and molecule

Answer 10

• An atom is the smallest part of an element
• A molecule is 2 or more atoms bonded together

Question 11

What is filtration used for

Answer 11

• Filtration is used to seperate an insoluble solute from a solvent
• Pour the mixture through a filter paper with a beaker at the bottom to collect the liquid from the solution, the undissolved solid would be collected in the filter paper as residue

Question 12

What is simple distillation used for

Answer 12

• Used to seperate a liquid from a solution
• Solution is boiled, the water vapour is condensed back into a liquid when it goes through the condenser and the solute is left behind

Question 13

What is fractional distillation used for

Answer 13

• Used to seperate liquids with different boiling points

Question 14

What is crystillisation used for

Answer 14

• Used to seperate a soluble solid from a liquid
• Place solution in evapourating basin, put in water bath. Once solvent is evapourating and crystals start forming, stop heating and leave to cool, filter to remove crystals and leave in warm place to dry

Question 15

How to set up a chromatogram

Answer 15

• Use a pencil line as a reference line
• Add spots of ink/dye to reference line
• Place filter paper in solvent (make sure solvent level is below pencil line)
• Leave until solvent nearly reaches the top of the paper
• Allow to dry, furthest dot have the greatest solubility

Question 16

Atomic number
Mass number (nucleon number)

Answer 16

• Number of protons found in an atom
• Number of protons and neutrons in an atom

Question 17

Isotope
Relative Atomic Mass

Answer 17

• Atoms of the same element with same number of protons, different number of neutrons
• The average mass of an atom compared to 1/12th the mass of carbon-12

Question 18

Metals

Answer 18

• Metals are good conductors of electricity
• Are malleable and ductile
• High melting and boiling point
• Metal oxides are basic, reacting with acids to form salt + water

Question 19

Non metals

Answer 19

• Poor conductors of electricity
• They are dull
• Low melting a boiling points

Question 20

What is an emperical formula

Answer 20

It shows the simplest whole number ratio between atoms in a compound

Question 21

What is a molecular formula

Answer 21

It shows how many atoms of each element are in a compound

Question 22

How are ions formed

Answer 22

• Ions are formed when atoms loose or gain electrons to become stable

Question 23

What is ionic bonding

Answer 23

• Ionic bonding is the strong electrostatic attraction between oppositely charged ions.

Question 24

What is a covalent bond

also talk about their attraction

Answer 24

• A covalent bond is formed when two non metals share electrons to fill their outer shells
• There’s a strong electrostatic attraction between the positively charged nuclei of the atoms and the negatively charged shared electrons

Question 25

Why do simple molecular structures have low melting point

Answer 25

• Within each molecule are atoms bonded covalently (strong forces)
• However between each molecule are weak forces of attraction which require little energy to break

Question 26

Why do large molecules have high boiling points?

Answer 26

• This is because they have more forces of attraction which requires more energy to overcome

Question 27

What is an allotrope

Answer 27

• Different forms of the same element

Question 28

Properties of Diamond

Answer 28

• Each carbon atoms is bonded to 4 other carbon atoms
• They have strong covalent bonds which require lots of energy to break
• It’s extremely hard because it has a giant covalent structure with many strong covalent bonds

Question 29

Properties of Graphite

Answer 29

• Each carbon atom is bonded to three other carbon atoms
• They have many strong covalent bonds and require a lot of energy to break
• It can conduct electricity because it has a delocalised electron even though it is non metal
• It’s soft and slippery because it’s arranged in layers which have weak intermolecular forces between them (they can slide over each other) and requires little energy to break

Question 30

Properties of C60 Fullerene

Answer 30

• It’s a simple molecular structure which means it has a low melting point due to the weak intermolecular forces between the molecules which doesn’t require lots of energy to break
• It doesn’t conduct electricity because the delocalised electron isn’t free to move therefore it can’t carry current

Question 31

What is metallic bonding

Answer 31

• Metallic bonding is the electrostatic attraction between positive metal ions and a sea of delocalised electrons

Question 32

Physical properties of metals

Answer 32

• They’re good conductors
• They are malleable because they’ve layers of ions that can slide over each other