Elements, Compounds and Mixtures

Question 1

What is matter?

Answer 1

Matter is anything that has mass and volume

Question 2

Types of mixtures

Answer 2

Heterogeneous and homogeneous mixtures

Question 3

What is the description of electrical conductivity - give an example

Answer 3

Ability to transmit electricity,

example - copper used in electrical wiring

Question 4

What is the description of heat conductivity - give an example

Answer 4

Ability to transfer heat energy, example - aluminum in saucepans

Question 5

What is the description of density - give an example

Answer 5

Mass to volume ratio, example - density of water = 1g/ml

Question 6

What is the description of melting point - give an example

Answer 6

Temperature at which a solid becomes a liquid, example - 0 degrees Celcius for water

Question 7

What is the description of boiling point - give an example

Answer 7

Temperature at which a liquid becomes a gas, example - 100 degrees Celcius for water

Question 8

What is the description of refractive index - give an example

Answer 8

How light passing through a material is bent, example - 1.33 for water

Question 9

What is the description of malleability - give an example

Answer 9

Ability to be shaped by hammering, example - gold jewellery

Question 10

What is the description of ductility - give an example

Answer 10

Ability to be shaped by pulling into a wire, example - Tantalum

Question 11

What makes a property intensive - give examples

Answer 11

Do not depend on the amount of matter present
can be used to identify substances
examples -density, colour, and boiling point

Question 12

What makes a property extensive - give examples

Answer 12

depends on the amount of matter present

examples - mass, volume and weight

Question 13

Properties of pure substances

Answer 13

• fixed composition
• properties do not vary
• cannot be separated into simpler substances by physical methods
• can only be changed in identity and properties by chemical methods

Question 14

what is an element

Answer 14

• an element is the simplest form of matter that has a unique set of properties
• cannot be split up into two or more simple substances by chemical means

Question 15

what is a compound

Answer 15

a compound is a substance that contains two or more elements chemically bonded in a fixed proportion e.g. water = H2O

Question 16

Properties of mass

Answer 16

nucleus - contains almost all of an atom’s mass

Question 17

what is relative atomic mass

Answer 17

the weight of an atom

Ar = mass of 1 atom of element / 1/12 x mass of 1 atom of carbon-12

Question 18

what is the formula for relative molecular mass

Answer 18

Mr = mass of 1 molecule of substance / 1/12 x mass of 1 atom of carbon-12

Question 19

describe homogeneous matter

Answer 19

• single phase
• same properties throughout the mixture
• uniform in appearance
• includes solutions

Question 20

describe heterogeneous matter

Answer 20

• multiple phases
• variable properties within a sample
  non-uniform in appearance
  colloids are visually homogenous but microscopically heterogeneous

Question 21

name 6 types of separation techniques

Answer 21

• filtration
• crystallization
  extraction
  evaporation
  magnetisation
  chromatography