iiiiii the periodic trend. ysize of atom atomic radius
TRANSCRIPT
Atomic Radius - Groups
Atomic radius increases as you move down a group
Why?Atomic size increases
because more electrons are added which results in more orbits.
Atomic Radius - Periods
Atomic radius decreases as you move across a period
Why?Increased (+) nuclear charge pulls the (-)
electrons closer to the nucleusAtomic size decreases
IONIC RADIUS
Ions are charged atoms, either +ve or –ve
Cations are +ve and form when atoms lose electrons
Anions are -ve and form when atoms gain electrons
Ionic Radius – Cations Group
Cations are smaller than their parent atoms.
Why?By losing electrons they
become shorter
Ionic Radius – Anions Groups
Anions are larger than their parent ions
Why?When extra (-) electrons
are added, the size of atom becomes bigger.
ELECRTONEGATIVITY
Ability of an atom to attract electrons toward itself in a chemical bond.
The difference between the electronegativities of two atoms determines what kind of bond they form.
Electronegativity - Periods
Electronegativity increases going left to right across the periodic table.
Fluorine has the highest. Lithium has the lowest.
Li Be B C N O F
1.0 1.5 2.0 2.5 3.0 3.5 4.0
Electronegativity - Groups
Electronegativity decreases going down a group
WHY??As atoms get bigger the
bonding electrons are far from the attraction of the nucleus.
H 2.1
Li 1.0
Na 0.9
K 0.8
Rb 0.8
Cs 0.7
Fr 0.7