PERIODIC TRENDS:1. ATOMIC RADIUS

2. IONIC RADIUS

What is the atomic radius? What is an ion? What is the ionic radius?

How does it change going across and down?

What is a radius?• Half of diameter as measured from center of

circle

What is an Atomic Radius?• half of the distance between the two adjoining

nuclei of atoms

Some elements occur stuck together naturally!

What are the seven diatomic elements?

• Diatomic Elements: two elements joined together

• Bromine (Br2)

• Iodine (I2)

• Nitrogen (N2)

• Chlorine (Cl2)

• Hydrogen (H2)

• Oxygen (O2)

• Fluorine (F2)

Made easy to remember….

Br I N Cl H O F

(like a last name Brinclhof)

Br I N Cl H O F Where are they on the periodic table?

Atomic Radius TrendIn groups = as atomic number increasesIn periods = as atomic number increases

Is there a part missing?

Trends show general rules

WHY?• In groups: adding more energy levels

• In periods: size of nuclear charge

What is an ion?• A ✚ or − charged atom• Occurs when atom loses or gains electrons

CATION• see a + ion• metals lose e- and become more +• become smaller

Atom:11 p+12 n11 e-

n=3

Overall charge = 0

Ion:11p+12 n10 e-

n=2

Overall charge = +1

ANION• A negative ion , a – ion• NONmetals gain e- and become more –• become larger

Atom9 p+9 e-

Overall Charge = 0

Ion9 p+10 e-

Overall Charge = -1

IONIC RADIUS TREND• Ionic size changes b/c:• CATIONS get smaller as e- are drawn in closer by +

nuclear charge

• ANIONS get bigger as e- cloud spreads out

IONIC RADIUS TREND• In groups = increase as you go b/c more energy

levels

• In periods = as you go across b/c e- cloud shrinks as e- are lost