M1-S1 Properties of Matter

  • Explore homogeneous mixtures and heterogenous mixtures through practical investigations:
  • Using separation techniques based on physical properties (ACSCH026)

Different types of matter

  • All matter can be categorized into three primary forms: 
  1. Elements
    • An element is a pure substance which is composed of only one type of atom. What is characteristic of elements is that they cannot be broken down into other substances physically nor chemically. All of the different types of elements can be found on the periodic table
    • Examples of elements include; oxygen (O). Hydrogen (H), Iron (Fe)
  1. Compounds
    • A compound is also a pure substance which contains two or more different elements which have been chemically combined or “bonded” in a fixed ratio. The property of the compound is detached from those of the elements which it is composed of. Because compounds are formed by the chemical bonding of multiple elements, they are able to be broken down chemically into these individual elements.
    • Examples of elements include; water (H2O), carbon dioxide (CO2) 
  1. Mixtures
    • A mixture contains two or more types of elements and/or compounds in any proportion. The difference between a mixture and a compound is that the components of a mixture are only physically combined and not chemically bonded. The components of a mixture keep their own properties and can be separated using physical methods.
    • Examples of mixtures include salt water (water H2O, and table salt NaCl), air (Nitrogen gas N2, Oxygen gas O2)

 

Homogeneous mixtures vs Heterogenous mixtures

 

  • Mixtures can either be classified as being homogeneous or heterogenous 
  1. Homogeneous Mixtures
    • A homogenous mixture is a mixture where the components that make up the mixture are distributed evenly throughout. The composition of the mixture is the same no matter which section of it you choose to extract and only shows one phase of matter so you wouldn’t see both a gas and a liquid in a homogenous liquid.
    • An everyday example of a homogenous mixture is air. Air is a mixture which consists of nitrogen, oxygen, argon, carbon dioxide and small trace amounts of other gases. No matter where air is collected from, if it is sampled, the composition of it will be the same

 

  1. Heterogeneous Mixtures
    • A heterogenous mixture is a mixture where the distribution of components is not uniform throughout and has a different composition throughout.
    • An example of a heterogenous mixture this is a cup of soda with ice cubes in it. The ice floats to the top of the water leaving the bottom of it only consisting of drink. 

 

Below is a table listing the different properties of Mixtures and Pure substances

 

Mixture

Pure Substance

·       A mixture can be physically separated into two or more pure substances by physical or mechanical means such as filtering, boiling or decanting

·       A pure substance cannot be separated into two or more substances by physical means. A compound can however be separated into elements using chemical means such as electrolysis (however beware that this is beyond the scope of the year 11 NESA science syllabus course content)

·       A mixture may be both homogenous or Heterogenous

·       A pure substance can only exist in homogenous form

·       A mixture will display the properties of all of the individual pure substance components which make it up. If a mixture is homogenous, different parts of it may show different properties

·       Has constant properties such as appearance, colour, density, melting point, and boiling point

·       The composition of a mixture is variable

·       The composition of a pure substance is fixed

 

Summary: Types of Matter 

  • Pure substances consist of either elements or compounds
    • An element is a substance which is composed of only one type of atom
    • A compound is a substance which is composed of chemically bonded elements in a fixed ratio and does not necessarily exhibit the same properties as elements
  • Matter can also be categorised as mixtures
    • A mixture contains two or more elements and/or compounds in the same physical state (gas, liquid, solid). It exhibits the properties of all components and can be physically separated into the pure substances which it consists of
  • Mixtures and pure substances can be categorised as either homogenous or heterogenous
    • Both mixtures and pure substances can be homogenous meaning that they have a uniform composition, but mixtures can also be heterogenous meaning that their composition is not uniform
    • Heterogenous mixtures can be separated into homogenous pure substances.