Periodicity and Properties of Elements

• what are the four polyatomic ions?

  Nitrate, sulfate, carbonate, and hydroxide.
• what are the chemical formulas for the four polyatomic ions?

  Nitrate: NO3- Sulfate: SO4^2- Carbonate: CO3^2- Hydroxide: OH-
• what does the strength of an ionic bond depend on?

  Charge and distance
• what do the strength of covalent bonds depend on?

  Electronegativity and bond length.
• what is electronegativity?

  the measure of an atom's ability to attract electrons in a chemical bond.
• what affects electronegativity?

  Atomic number, distance from the nucleus, and shielding.
• what happens when there is a difference in electronegativity?

  Polar covalent bond because the electrons are shared unequally.
• what are the physical properties of metals?

  malleability, ductility, and conductivity.
• what are the 2 reasons why metals are good conductors of heat?

  at higher temperatures the metal atoms vibrate more passing this energy onto their neighbouring atoms and free electrons carry energy through the metal
• why are metals good conductors of electricity?

  they have a high density of free electrons that can move freely through the metal structure
• what happens to the melting point as you go down a group and why?

  it decreases because the distance between the nucleus and the delocalised electrons are bigger which means the forces holding the structure together are weaker
• why do group 2 have higher melting points than group 1?

  Increased nuclear charge results in stronger metallic bonding, leading to higher melting points.
• what are the properties of van der waal forces?

  very weak

  attraction only lasts for a short time