Chemistry - Atomic structure and the Periodic Table

  1. Describe the structure of the atom.

    • The central nucleus containing neutrons and protons, surrounded by electrons in shells

  2. State the relative charges and relative masses of a proton, a neutron and an electron

    • Protons: +1 and relative mass of 1

    • Neutrons: 0 (neutral) and relative mass of 1.

    • Electrons: -1, relative mass approximately 1/1836 of a proton.

  3. Define proton number / atomic number

    • number of protons in the nucleus of an atom

  4. Define mass number / nucleon number

    • total number of protons and neutrons in the nucleus of an atom

  5. Determine the electronic configuration of elements with proton number 1 to 20, e.g. 2,8,3

  6. State that:

  • Group VIII noble gases have a full outer shell

  • the number of outer-shell electrons is equal to the group number in Groups I to VII

  • the number of occupied electron shells is equal to the period number

  1. Define isotopes

    • different atoms of the same element that have the same number of protons but different numbers of neutrons

  2. State that isotopes of the same element:

    • have the same chemical properties because they have the same number of electrons and therefore the same electronic configuration

  1. Describe the Group I alkali metals, lithium, sodium and potassium, as relatively soft metals with general trends down the group, limited to:

    1. (a). decreasing melting point

    2. (b). increasing density

    3. (c). increasing reactivity with water

  1. Describe the Group VII halogens, chlorine, bromine and iodine, as diatomic non-metals with general trends down the group, limited to:

    1. (a). increasing density

    2. (b). decreasing reactivity

  2. State the appearance of the halogens at room temperature and pressure, r.t.p., as:

    1. (a). chlorine, a pale yellow-green gas

    2. (b). bromine, a red-brown liquid

    3. (c). iodine, a grey-black solid

  3. Describe and explain the displacement reactions of halogens with other halide ions:

    • In displacement reactions, a more reactive halogen will displace a less reactive halogen from its compound.

    • For example, when chlorine gas is bubbled through a solution of potassium bromide, bromine is formed as chlorine displaces bromine due to its higher reactivity.

    • Similarly, iodine will not displace either chlorine or bromine from their respective halide ions, as it is the least reactive among them.  

  4. Predict the properties of other elements in Group VII, given information about the elements:

    • Fluorine: The most reactive halogen, capable of displacing others due to its strong electronegativity and small atomic size, resulting in formation of compounds with various elements.

    • Astatine: Less reactive than iodine, it may show varied displacement behavior due to its larger atomic radius and lower electronegativity, potentially not displacing lighter halogens.