Trends in the periodic table:

Background• Electrons can jump between shells (Bohr’s

model supported by line spectra)• The electrons can be pushed so far that

they escape the attraction of the nucleus• Losing an electron is called ionization• An ion is an atom that has either a net

positive or net negative charge• Q: what would the charge be on an atom

that lost an electron? Gained two electrons?• A: +1 (because your losing a -ve electron)• A: -2 (because you gain 2 -ve electrons)

PERIODIC TRENDS IN ATOMIC SIZE

Atomic size generally increases down a group.Atomic size generally decreases from left to right across a period

PERIODIC TRENDS IN IONISATION ENERGY

When an atom gains or loses an electron it forms an ion.The energy required to remove an electron from a gaseous atom is known as the ionisation energy

The first ionisation energy decreases moving down a group The first ionisation energy increases moving left to right across a period

PERIODIC TRENDS IN IONIC SIZE The atoms of metallic elements have low ionisation energies

and form positive ions easily. Cations (+ve ions) are always smaller than the neutral

atoms from which they are formed due to increased attraction by nucleus for remaining electrons

The atoms of non-metallic elements readily form negative ions Anions (-ve ions) are always larger than the neutral atom

from which they are formed.

PERIODIC TRENDS IN ELECTRONEGATIVITY Electronegativity of an

element is a measure of the degree too which an atom can attract an electron to itself. (Pauling’s scale).

Each atom, except the noble gases, is assigned an arbitrary number. F – 4.0, Cs & Fr 0.7

Electronegativity; increases across a period

left to right Decreases down a group

PERIODIC TRENDS IN METALLIC CHARACTERISTICS

Metallic character decreases across a period and increases down a group.

PERIODIC TRENDS IN OXIDISING AND REDUCING STRENGTH

An oxidant causes oxidation by gaining electrons but is itself reduced. An oxidant is also called an oxidising agent

A reductant causes reduction by losing electrons but is itself oxidised. A reductant is also called a reducing agent.

REVIEW Alkali metals on line multiple choice Halogens on line multiple choice Transition metals, noble gases on line multiple choice

Complete the revision questions page 167 (14 – 16)

Complete the multiple choice questions pages 168, 169 (1 – 11)

Complete the review questions 1, 6, 8, 9, 10, 13

Complete the exam practice questions 1, 3 Periodic Table on line questions