Atoms and Elements

Atoms and Elements

1. Describe the differences between elements, compounds and mixtures

   • ELements- Substance only made of one type of atom
   • Compounds- Substance made from more that one type of atom.
   • MIxture- Substance which has more than one type of element but not chemically bonded together

2. Describe the structure of an atom in terms of electrons and a nucleus containing protons and neutrons

   • An atom has a nucleus in middle containing protons and neutrons surrounded by shells containing electrons

3. Describe the build-up of electrons in ‘shells’ and understand the significance of the noble gas electronic structures and of valence electrons.

   • Each atom has outer shells containing electrons. The first outer shell of an atom is capable of containing only 2 electrons while the other can contain up to 8 electrons. Noble gases structure is the outer shell is filled and there is no more need for electrons for a complete outer shell.

4. State the relative charges and approximate relative masses of protons, neutrons and electrons

5. Define atomic (proton) number and mass (nucleon) number

   • Atomic number- number of proton.
   • Nucleon number- number of proton and neutron

6. Define isotopes

   • Isotopes are the atoms of the same element which have the same number of the proton but a different nucleon number.

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