Reactions

You can have a chemical or physical change

Physical properties include:

  • colour

  • melting point

  • boiling point

Physical change:

Changes in the physical properties

  • melting

  • boiling

  • condensation

    no change occurs in the identity of the substance

Chemical change, the chemical substance does change

The physical change doesn’t change composition of particular substance

All chemical reactions involved the creation of new substances and associated energy transformations

Energy transformations: evident in changes in the temperature of the surroundings and/or the emission of light

Bonds are stored chemical energy

Chemical reactions

  • Chemical reactions show how 1 set of substances chemically changes into a new set of substances. The number and type of atoms present stays the same but the arrangement of how the atoms are bonded

  • Reactants and products

  • Can either combine things, break down or rearrange to do chemical reactions

LAW OF CONSERVATION OF MASS

  • The law of conservation of mass states: the mass of the products is equal to the mass of the reactants

  • No new atoms are created, and none are destroyed. Mass is conserved

  • The products and reactants need to have equal numbers of atoms of each element

  • We use coefficients to show the conservation of mass in a chemical reactions