Atomic Structure and the Periodic Table

    Cards (64)

    • atom
      the smallest unit of matter
    • element
      a substance made of only 1 type of atom
    • molecule
      a substance made of two or more atoms joined together by a bond
    • compound
      a substance made of at least two different types of atom chemically bonded together
    • mixture
      two or more substances that are mixed together but are not joined by bonds
    • chemical symbol

      the letters on the periodic table that give the name of each element, every element has its own chemical symbol
    • chemical formula
      the collection of chemical symbols that show how many of each element are present in a molecule or compound
    • nucleus
      the centre part of an atom that contains the protons and neutrons
    • proton
      sub-atomic particle that makes up the nucleus of an atom, has a mass of 1 and a charge of +1
    • neutron
      sub-atomic particle that makes up the nucleus of an atom, has a mass of 1 and a charge of 0
    • electron
      sub-atomic particle found orbiting the nucleus in an electron shell, has a mass of almost 0 and a charge of -1
    • ion
      an atom that has lost or gained electrons to become charged, lost electrons leave a positive ion, gained electrons leave a negative ion
    • conservation of mass
      a rule that says you must have the same amount of atoms at the end of a chemical reaction as you started with
    • chemical equation
      a way of showing what happens in a chemical reaction using the chemical symbols and formulae of the substances
    • balanced equation

      a chemical equation written so that there are the same number of each type of atom on each side of the equation
    • atomic number
      the smaller number next to the chemical symbol that identifies an element and gives the number of protons and electrons in that atom
    • mass number
      the larger number next to the chemical symbol of an element that measures the mass of the atom (Mass number = number of protons + number of neutrons)
    • electron shell
      one of the regions outside of the nucleus where electrons can be found
    • electronic structure
      a diagram showing how the electrons are arranged in the electron shells (the 1st shell can have a maximum of 2 electrons, the others can hold up to 8 electrons)
    • filtration
      a technique used to separate an insoluble substance from a solvent (one that does not dissolve)
    • crystallisation
      a technique used to separate a soluble solid (or salt) from a solution
    • distillation
      a technique used to obtain the solvent (or liquid) from a solution
    • fractional distillation
      a technique used to separate two miscible liquids (ones that do mix together)
    • chromatography
      a technique commonly used to separate a mixture of dyes in ink
    • J.J. Thomson
      the scientist who discovered the electron and proposed the plum pudding model
    • plum pudding model

      a model of the atom that proposed the nucleus was a ball of positive charge with negative electrons embedded in it (we now know this is incorrect)
    • Rutherford's experiment
      the experiment that proved the nucleus must be positively charged (as alpha particles were scattered/deflected by a piece of gold foil)
    • Niels Bohr
      the scientist who proposed that electrons are found in shells
    • James Chadwick
      the man who proposed the existence of neutrons
    • isotope
      atoms of the same elements with the same atomic number but different mass numbers (different numbers of neutrons in the nucleus)
    • How are elements arranged in the periodic table?

      Ordered by increasing atomic number.

      Elements in the same group (column) have the same number of outer shell electrons.

      Elements in the same period (row) have the same number of electron shells.
    • Describe alkali metals
      The elements in group 1 (found on the left hand side of the periodic table) are called the alkali metals.
      They have 1 electron in their outer shell.
      This electron is usually given away in chemical reactions.

      These metals are soft and have relatively low melting points. They are very reactive because they easily lose the electron in their outer shell.
    • Why are group 1 elements called alkali metals?
      Because they react with water to form alkaline solutions
    • Why should alkali metals be stored in oil?
      To prevent them from reacting water vapour and oxygen in the air
    • What happens when alkali metals react with oxygen?
      Rapidly turns from silvery shiny to dull as a metal oxide (e.g. potassium oxide) is produced.
    • What happens when alkali metals react with chlorine?

      A metal chloride is formed (e.g. sodium chloride), which dissolves in water to give a colourless solution.
    • What happens when alkali metals react with water?
      The metal floats on the surface and melts to create a metal hydroxide (e.g. lithium hydroxide).

      When they react with water, the energy released is enough to melt the metal.
    • Reactivity of lithium with water
      It is the least reactive of the alkali metals.

      Lithium fizzes steadily and floats, becoming smaller until it eventually disappears.
    • reactivity of sodium with water
      It's more reactive than lithium because its outer electron is less strongly attracted to the positively charged nucleus.
      This is because it is further away from the positive charge of the atom's nucleus.

      Sodium fizzes rapidly and melts to form a ball that moves around on the water's surface.
    • Reactivity of potassium with water
      Potassium is the most reactive so reacts very quickly.
      It's more reactive than lithium and sodium because its outer electron is least strongly attracted to the nucleus.

      The hydrogen produced ignites instantly and the metal quickly melts to form a ball which also sets alight, sparking and burning with a lilac flame.