Elements, compounds and mixtures

Question 1

What is Matter?

Answer 1

Anything that has mass and volume

• states of matter:
  •solids
  •liquids
  •gases

Question 2

Name some properties of matter

Answer 2

• electrical conductivity
• heat conductivity
• density
• melting point
• boiling point
• malleability
• ductility
• refractive index

Question 3

Compare intensive and extensive properties

Answer 3

• intensive properties do not depend on the amount of matter present e.g density, colour and boiling point
• extensive properties depend on the smoking of matter present e.g mass, volume, weight

Question 4

Compare physical and chemical properties

Answer 4

• physical properties are observed by examining a sample of pure substance
• chemical properties are observed in the course of a chemical reaction

Question 5

State features of Pure substances

Answer 5

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

Question 6

What are the types of pure substances?

Answer 6

• Elements

- Compounds

Question 7

State the atomic theory

Observation: elements combine in fixed ratios

Answer 7

• All matter is composed of atoms
• Different elements have different types of atom
• Atoms cannot be made or destroyed
• compounds are composed of two or more atoms chemically combined
• chemical reactions arrange the atoms, changing ratios of the chemical combination - therefore identity of compounds

Question 8

What are the properties of atoms?

Answer 8

• Mass 
- nucleus ( contains almost all of an atoms mass)
- protons 
- neutrons 
- electrons 
• combining power 
- also termed “valency”
- ability to form chemical bonds

Question 9

What is the formula for Relative atomic mass?

Answer 9

Relative atomic mass = Mass of 1 atom of element / 1/12 x mass of 1 atom or carbon-12

Question 10

What is a molecule?

Answer 10

Units of two or more atoms atoms helps together by chemical bonds

Question 11

State features of a mixture

Answer 11

• Variable composition
• Components retain their identity
• Separable into pure substances by physical methods

Question 12

What is the difference between Homogenous and heterogenous mixtures?

Answer 12

Homogenous mixtures are a single phase and have the same properties throughout the mixture and have a uniform appearance where as heterogenous mixtures are a multiple phase and have variable properties within a sample, non- uniform appearance

Question 13

What are some basic separation of mixture techniques?

Answer 13

• Filtration
• Cryztalkization
• Extraction
• Distillation
• chromatography