chemistry chapter 3 and 4

• Atoms

  Atoms are the smallest particles of matter that we cannot break down further by chemical means.

  Particles of atom consist of proton,neutron,electron.
• element


  An element contains only one kind of atom.
• every atom has an equal number of protons and electrons.So atoms have no overall changes.
• The total number of protons and neutrons in an atom is called nucleon number.
• isotopes 


  istopes are atoms of the same element with different number of neutrons.
• electrons shell

  electrons are arranged in shells around the nucleus.
• the period number in a periodic table tells you how many shells there are.
• metals and non metals

  metals and non metals are seperated by the line shown in the photo.

  A) metals and non metals are seperated by the line.

  
• compounds

  compound is made of atoms of different elements,bonded together.
• waters formula

  H2O
• mixture 


  a mixture contains different substances that are not bonded together.
• signs of chemical change

  1.One or more new chemical substances are formed

  2.Energy is taken in or given out,during the reaction

  3.The change is usually difficult to reverse.
• chemical change


   A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.
• physical change

   the material involved in the change is structurally the same before and after the change