C1 Revision

C1 Revision

1. ATOMS AND ELEMENTS

   • ATOM: The smallest particle of a chemical element that can exist.
     • ELEMENT: A substance which only contains one type of atom.
       • MOLECULE: Two or more atoms held together by chemical bonds.
         • COMPOUND: Two or more elements that are chemically joined.
   • PROTON: A subatomic particle that is found in the nucleus, it has a positive charge
     • ELECTRON: A subatomic particle with a negative charge. These are found on the outer shell of an atom.
       • NEUTRON: A subatomic particle that has no charge and is found inside the nucleus.
       • ATOMIC NUMBER: Each element has a set number of protons and will always have that number.This is called the atomic number! Every atom has the same number of protons and electrons.
         • The atomic number is always the smallest number out of the two.
   • ISOTOPES: Elements that have a different number of neutrons.
     • Isotopes all have the same chemical reactions but they might have diiferent mealting points and different densities

2. GROUPS AND ROWS ON THE PERIODIC TABLE.

   • Groups are the columns in the periodic table, the group number tells us how many electrons are on the outer shell.
     • GROUP 1 elements are called Alkali metals.
       • GROUP 7 elements are called Halogens
         • GROUP 8 elements are called Noble Gases
         • All halogens go round in pairs.
   • The period (sometimes called rows) tells us how many shells are being filled with electrons.

3. MELTING POINT, BOILING POINT AND DENSITY MEANING:

   • MELTING POINT: the temperature that a solid becomes a liquid.
   • BOILING POINT: the temperature that a solid becomes a gas.
   • DENSITY: the size of a volume (g/cm3)

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