Chemistry

Chemistry

1. Atoms

   • All matter is made up of atoms.
   • At the centre of the atom is the nucleus.
   • The nucleus contains two types of subatomic atoms:
     • Protons - large particles with a positive charge.
     • Neutrons - large uncharged particles.
   • The nucleus is the heaviest part of the atom.
   • Electrons are very small, negatively charged particles that rapidly move around the nucleus.

2. Atomic Number

   • The number of protons in an atom tells us which element it is.
     • E.g. Carbon atoms all have six protons in their nucleus.
     • E.g. Hydrogen atoms all have one proton in its nucleus.
     • E.g. An atom with three protons MUST be Lithium.
   • the number of protons is called the Atomic Number.
   • A neutral atom has the same number of electrons as it has protons

3. Mass Number

   • The number of neutrons in an atom is not necesarily the same as the number of protons or electrons.
   • The total number of protons and neutrons in the nucleus of an atom is called the Mass Number.

4. Isotopes

   • Atoms of the same element always have the same number of protons
   • They may have different numbers of neutrons.
   • These atoms are isotopes of each other.
   • They will have different mass numbers.
   • The average of the isotopes equal to the mass numbers decimal.

5. Radioactivity

   • Types of radioactive particles
     • Alpha radiation
       • Alpha decay can be thought of as nuclear fission between nuclei because the parent nucleus splits into two daughter nuclei.
     • Beta radiation
       • When there is an abundance of neutrons and protons in the nucleus, a neutron may change into a proton and electron. The electron is then released as a beta particle.
     • Gamma radiation
       • Gamma radiation is in the from of electromagnetic waves.
       • Sometimes when an alpha or beta particle is released from the nucleus, the new nucleus is unstable and gives out extra energy in the from of a gamma ray to become more stable.
   • Uses and dangers
     • Uses
       • Nuclear
     • Dangers
       • Nuclear radiation can have a devastating effect on living things. Exposure to large doses of radiation can cause immediate effects such as nausea, headaches, vomiting and diarrhoea. Nuclear radiation damages living cells and too much exposure can lead to diseases such as leukaemia and cancer. It can also damage the reproductive mechanisms in cells, including DNA, leading to birth defects in the offspring of exposed organisms.
   • Dating using radioactive isotopes