SC17-19

• what are group 1 elements known as?

  alkali metals
• how many electrons are in the outer shell of group 1 elements?

  1
• which alkali metal is the least reactive?

  lithium
• what colour flame is produced when lithium reacts with oxygen?

  crimson
• what happens when lithium reacts with water?

  it will float on the surface and will release bubbles of hydrogen gas (effervescence).
• why is sodium more reactive than lithium?

  sodium's outer electron is less strongly attracted to the positively charged nucleus. This is because it is a greater distance from the positive charge of the atom's nucleus.
• what colour flame is produced when sodium reacts with oxygen?

  yellow/orange
• what happens when sodium reacts with water?

  it floats on the surface which produces enough heat to melt the sodium. The sodium moves quickly across the surface of the water.
• why is potassium more reactive than sodium and lithium?

  it's outer electron is least strongly attatched to the nucleus.
• what colour flame is produced when potassium reacts with oxygen?

  lilac
• what happens when potassium reacts with water?

  the metal floats on the surface of the water, and has a similar, but more vigorous reaction compared to sodium.
• why are group 1 elements very reactive?

  because they easily lose the 1 electron in their outer shell.
• what happens to alkali metals when they react with water?

  rapidly turns from shiny to dull as a metal oxide is produced.
• what happens when alkali metals react with water?

  the metal floats on the surface and melts to create a metal hydroxide. When they react with water, the energy released is enough to melt the metal.
• what happens when alkali metals react with chlorine?

  a metal chloride is formed which dissolves in water to give a colourless solution.
• what happens when potassium reacts with COLD water?

  the hydrogen produced ignites instantly and the metal also sets alight, sparking and burning with a lilac flame.
• what happens when sodium reacts with COLD water?

  fizzes rapidly and melts to form a ball that moves around on the surface of the water.
• what happens when lithium reacts with COLD water?

  fizzes steadily and floats, becoming smaller until it eventually disappears.
• the atoms gain more electron shells as you go down group 1
• the attraction between positive nucleus and negative outer electron becomes weaker as you go dwon group 1 as the outer electron is further way from the nucleus.
• as you go down group 1, what happens to the reactions?

  quicker and more vigorous.
• what is produced when group 1 metals react with cold water?

  • metal hydroxide
  • hydrogen gas
• what are group 7 elements also known as?

  halogens.
• how many electrons do halogens have in their outer shell?

  7
• what happens to halogens when they react?

  they gain 1 electron to have a full outer shell. By gaining 1 electron, they form a negative ion.
• halogens share electrons to form diatomic molecules (molecules made of pairs of atoms).
• what is formed when a metal atom transfers its outer electron to a non-metal atom (like a group 7 atom)?

  salts
• what happens to reactivity as you go down group 7?

  reactivity decreases as the atoms gain more electron shells. The outer electron shell is further away from the nucleus and so the attraction between the nucleus and the electron (to be gained from another element) decreases.
• what are the properties of halogens?

  • diatomic molecules
  • reactivity decreases as you go down the group
  • 7 outer electrons
  • form negative ions
• what state and colour is chlorine at room temp?

  pale gree, gas
• what state and colour is bromine at room temp?

  red/brown, liquid
• what state and colour is iodine at room temp?

  dark grey, solid
• what is the test for chlorine?

  insert damp litmus paper into a test tube containing a gas. If the gas is chlorine, the litmus paper will bleach and change colour from red to white.
• what are group 0 elements also known as?

  noble gases
• why are group 0 elements unreactive?

  they have a full outer shell of electrons so they do not gain or lose electrons to fill up this shell as it is already full.
• what are noble gases used in light bulbs?

  they will not reactive with the hot metal filament.
• what do noble gases exist as because they are unreactive?

  single atoms (monatomic) instead of forming molecules.
• what happens to the boiling points of noble gases as you move down?

  they increase because the relative atomic mass increases as you go down the periodic table.
• noble gases have low boiling points.
• noble gases have low density.