The Periodic Table

• atomic number

Periodicity

Atomic Radius

• definition - distance between nucleas and the outermost orbital

  • increase down group

  • decrease across a period

Density

• density increase from g1 → to middle of the table

• general decrease from middle to group 8

• period 3 has higher density than group 2

Melting Point

• metals increase across period

• non metals decrease across a period

• decrease down group

• non-metals increase down groups

Boiling Points

• of metals increase across period

• non metals decrease across period

• decrease down group

• non metals increase down groups

= melting point = boiling point

Ionisation Energy (removing an electron)

• definition - ionization energy of an element is the amount of energy required to remove an electron from a gaseous atom to form a cation.

  • higher ie means that it is more difficult to remove an electron

• Trends

  • IE increase across periods ( an extra proton and electron means that their is higher attraction froce)

  • new period means less IE (electrons are added to a new shell further from the nucleus = weaker electrostatic forces)

Metal - cation

Non-Metal - anion

Electron Affinity

the energy change when an electron is added to a gaseous atom to form an anion.

• defintion - the energy change when an electron is added to a gaseous atom to form an anion.

• trends

  • increases across period (metal lower than non metal)

  • electron affinties of halogens are highest (accepting an electron = attain noble gas config. of noble gas next to them)

Electronegativity (electron greedyness)

definition - the ability of an atom in a compound to attract the bonding electron pair(s)

• nonmetals greedier

• increase from 1 → then restarts

Chemical Properties among Elements

• determined by no of valence electron that need to be lost or gained to obtain fill outer shell

  • loss of electrons = postive cation

  • gain electron = negative anion

Group 1 - Alkali metals

• reacts vigirously with water

• increase down

• very reactive

• low IE

Group 2 - Alkali earth metals

• less reactive than group one as more energy needed to remove second electron

• varied react in water

• increase down group

Group 7 - Halogens

• form diatomic molecules

• reacts group 1 to form salts

• decreases down group

• low meltings, boiling points

• room temp

  • first two gas, third liquid, last black solid

  • colourless, green-yellow, red-brown, purple-black

Inert/Noble gas

• full outer shell → unreactive

  • low boiling point

  • colourless

  • gases at room temp