Periodicity

Electron configuration based on position in TPT
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Electron configuration based on position in TPT
Group 1-2 and 13-18 --> group number indicate number of valence electrons.
Groups and periods
Groups: vertical
Periods: across
Elements are listed in terms of atomic number or proton number.
Position of non-metals, metals and metalloids
Metals: left of the staircase (incl. aluminium)
Metalloids (semi-metals): around the staircase
Non-metals: to the right of the staircase

Staircase: starts below B and zigzags down to Po and At.
alkali metals
Group 1
The most reactive group of metals - react strongly with cold water.
Halogens
Group 17
The most reactive group of non-metals - powerful oxidising agents.
Noble gases
Group 18
A group of very unreactive monatomic gases.
Transition metals
Group 3-13
Relatively stable metals with only moderate reactivity - useful for construction and with characteristic common properties (similar chemical and physical properties of the elements.)
Lanthanoids + actinoids
F block
Prediction + explanation of metallic behaviour of an element based on its position in TPT
Melting-point and electrical conductivity increases across a period.
Bonding: positive ions in giant lattice and sea of delocalised electrons. Bonding increases across a period, as more electrons holds it together.
Caesium is the most reactive.
Prediction + explanation of non-metallic behaviour of an element based on its position in TPT
Relatively small molecules covalently bonded with relatively weak London dispersion forces.
They do not conduct electricity.
Fluorine is the most reactive.

Metalloids (Si) can conduct electricity.
Construction of equations to explain the pH changes for reactions - oxides reacting with waterIonic: basic Na2O + H2O --> 2NaOH MgO + H2O --> Mg(OH)2 Covalent: acidic P4O10 + H2O --> 4H3PO4 SO3 + H2O --> H2SO4 More acidic across period (except group 18)PeriodicityIn Chemistry it refers to the phenomenon that, if the elements are arranged in order of increasing atomic number then a range of both chemical and physical properties show a repeated pattern.Blocks# of orbitals per energy level S 1 D 3 P 5 Lanthanoids + 7 ActinoidsAtomic radiiDecrease across the periods. Increase down a group. Ionic size increase down a group.First ionisation energyis the energy required to remove an electron from a gaseous atom. It increases from left to right across a period and decrease down a group. e- closest to positively charges nuclei is the hardest to remove. M (g) → M+ (g) + e- Difference between first ionisation energy of element in a period: Nuclear charge, energy level (or distance from the nucleus), and repulsion by other electrons (shielding).ElectronegativityAttraction between atom to its electrons in a covalent bond. Decrease down a group, because radii increase.