11/2/2015

1

PERIODIC PATTERNS Periodic Table Mini-Project

Mr. Fahad

What patterns exist on the

periodic table?

Lesson Essential Question:

11/2/2015

2

METALLIC TREND

INC

REA

SES

ATOMIC RADIUS

Radius is the distance from the center of the nucleus to the “edge” of the electron cloud.

Atomic radii are usually measured in picometers (pm) or angstroms (Å). An angstrom is

1 x 10-10 m.

11/2/2015

3

ATOMIC RADIUS

BROMINE =

Br2

Since a cloud’s edge is difficult to define, scientists use define covalent radius, or half the distance between the nuclei of 2 bonded atoms.

2.86 Å 1.43 Å 1.43 Å

11/2/2015

4

ATOMIC RADII TRENDS

As you go down a

family the n value

increases making the

radius larger.

DOWN A FAMILY OR GROUP WHY?

INC

REA

SES

ATOMIC RADII TRENDS

As you go across a

period the number of

protons increases,

(nuclear charge)

pulling the electrons in

tighter making the

radius smaller.

ACROSS A PERIOD WHY?

DECREASES

11/2/2015

5

IONS - remember

Metals Lose electrons

becoming positive.

Calcium – Ca

[Ar]4s2

Loses 4s2 e-s becoming

Ca+2 and [Ar] Noble gas

Configuration. (Octet Rule)

Nonmetals Gain electrons

becoming negative.

Chlorine – Cl

[Ne]3s23p5

Gains one e- becoming Cl-1 and [Ar] Noble gas configuration.

(Octet Rule)

IONS – How can I remember?

Metals Nonmetals

This is Ann ion - ANION

She is unhappy

and negative.

This is Cat-ion - CATION

He is a “plussy” cat!

11/2/2015

6

IONIC RADII TRENDS

As you go down a

family the n value

increases making the

radius larger.

DOWN A FAMILY OR GROUP WHY?

INC

REA

SES

IONIC RADII TRENDS

For the metals the nuclear charge is greater than then number of electrons pulling them in tighter making the radius smaller.

At the nonmetals the radius gets larger because the ion has gained electrons.

ACROSS A PERIOD WHY?

DECREASES then INCREASE

11/2/2015

7

METALLIC ATOM AND ION COMPARISON

NONMETALLIC ATOM AND ION COMPARISON

Why do the Noble

Gases not have an

ionic Radius?

11/2/2015

8

ATOM AND ION COMPARISON

Why does

Hydrogen not have

an ionic Radius?

As more electrons are added to atoms,

the inner layers of electrons shield the

outer electrons from the nucleus.

The effective nuclear charge on those

outer electrons is less, and so the outer

electrons are less tightly held

Shielding Effect

11/2/2015

9

Example of Shielding Effect

The energy required to remove an electron from an atom is ionization energy. (measured in kilojoules, kJ)

Ionization Energy

11/2/2015

10

IONIZATION ENERGY

The larger the atom is, the easier its electrons are to remove. Ionization energy and atomic radius are inversely proportional. Ionization energy is always endothermic, that is energy is added to the atom to remove the electron.

11/2/2015

11

IONIZATION TREND

INCREASES IN

CREA

SES

is a measure of the tendency of an

atom to attract a bonding pair of

electrons.

Electronegativity

11/2/2015

12

ELECTRONEGATIVITY

11/2/2015

13

In Summary…. Electronegativity

Ele

ctro

negativity