Atomic structure

Atomic Structure

The structure of the atom

ELECTRON

PROTON NEUTRON

Sub-atomic particles

Particle Charge Location mass

Proton Positive Nucleus 1 amu

Neutron Neutral Nucleus 1 amu

electron negative Orbits the nucleus

1/1842 amu

The Atom Hydrogen

Proton Electron

Hydrogen has one proton, one electron and NO neutrons

The Atom Helium

ElectronProton

Neutron

Helium has two electrons, two protons and two neutrons

Mass number and atomic number

MASS NUMBER: number of protons + number of neutrons

SYMBOL

ATOMIC NUMBER: number of protons (only)

How many protons, neutrons and electrons?

How shells fill

• The first electron shell can only hold a maximum of two electrons.

• The second electron shell can hold a maximum of eight electrons.

• The third electron shell can also hold a maximum of eight electrons.

• The fourth electron shell can also hold eight electrons.

The Atom Helium

ElectronProton

Neutron

Helium has two electrons, two protons and two neutrons

The Atom Lithium

Protons

Neutrons

Electrons

Lithium has three electrons, three protons and four neutrons.

The Atom Boron

Protons

Neutrons

Electrons

Boron has five electrons, five protons and six neutrons.

The Atom Oxygen

Protons

Neutrons

Electrons

Oxygen has eight electrons, eight protons and eight neutrons.

The Atom Sodium

Protons

Neutrons

Electrons

Sodium has eleven electrons, eleven protons and twelve neutrons.

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

HydrogenH

1 electron 0 electron 0 electron 0 electron

HeliumHe

2 electron 0 electron 0 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

LithiumLi

2 electron 1 electron 0 electron 0 electron

BerylliumBe

2 electron 2 electron 0 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

BoronB

2 electron 3 electron 0 electron 0 electron

CarbonC

2 electron 4 electron 0 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

NitrogenN

2 electron 5 electron 0 electron 0 electron

OxygenO

2 electron 6 electron 0 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

FluorineF

2 electron 7 electron 0 electron 0 electron

NeonNe

2 electron 8 electron 0 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

Potassium

2 electron 8 electron 8 electron 1 electron

CalciumCa

2 electron 8 electron 8 electron 2 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

SodiumNa

2 electron 8 electron 1 electron 0 electron

MagnesiumMg

2 electron 8 electron 2 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

AluminiumAl

2 electron 8 electron 3 electron 0 electron

SiliconSi

2 electron 8 electron 4 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

PhosphorusP

2 electron 8 electron 5 electron 0 electron

SulphurS

2 electron 8 electron 6 electron 0 electron

How the shells fill with electrons

Element Shell 1 Shell 2 Shell 3 Shell 4

ChlorineCl

2 electron 8 electron 7 electron 0 electron

ArgonAr

2 electron 8 electron 8 electron 0 electron

The Periodic table

Horizontal rows are called PERIODS

Vertical columns are called GROUPS

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Fe Ni Cu Zn Br Kr

Ag I Xe

Pt Au Hg

The Periodic TableElements in the same group have the same number of electrons in the outer shell (this

correspond to their group number)

E.g. all group 1 metals have 1 electron in their outer shell

These elements have __ electrons in their outer shell

These elements have 3 electrons in their outer shells

H He

Li Be B C N O F Ne

NaMg

Al Si P S Cl Ar

K Ca Fe NiCu

Zn Br Kr

Ag I Xe

PtAu

Hg

The Periodic TableAs you move down through the periods an

extra electron shell is added:

E.g. Lithium has 3 electron in the configuration 2,1

Potassium has 19 electrons in the configuration __,__,__

Sodium has 11 electrons in the configuration 2,8,1

H He

Li Be B C N O F Ne

NaMg

Al Si P S Cl Ar

K Ca Fe NiCu

Zn Br Kr

Ag I Xe

PtAu

Hg

The Periodic TableMost of the elements are metals:

These elements are metals

This line divides metals from non-metals

These elements are non-metals

H He

Li Be B C N O F Ne

NaMg

Al Si P S Cl Ar

K Ca Fe NiCu

Zn Br Kr

Ag I Xe

PtAu

Hg

The Periodic TableAll of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This

is called PERIODICITY.

E.g. consider the group 1 metals. They all:

1) Are soft

2) Can be easily cut with a knife

3) React with water

Group 1 – The alkali metals

Li

Na

K

Rb

Cs

Fr

Group 0 – The Noble gasesHe

Ne

Ar

Kr

Xe

Rn

Group 7 – The halogens

F

Cl

Br

I

At

The First Twenty Elements

• Hydrogen 1,0,0,0

• Helium 2,0,0,0

• Lithium 2,1,0,0

• Beryllium 2,2,0,0

• Boron 2,3,0,0

• Carbon 2,4,0,0

• Nitrogen 2,5,0,0

First 20 Elements continued

• Oxygen 2,6,0,0

• Fluorine 2,7,0,0

• Neon 2,8,0,0

• Sodium 2,8,1,0

• Magnesium 2,8,2,0

• Aluminium 2,8,3,0

• Silicon 2,8,4,0

First 20 Elements continued

• Phosphorus 2,8,5,0

• Sulphur 2,8,6,0

• Chlorine 2,8,7,0

• Argon 2,8,8,0

• Potassium 2,8,8,1

• Calcium 2,8,8,2

The Alkali metals

• Lithium, Sodium and Potassium have one electron in their outer shell and this is why they are found in group one of the periodic table.

The Nobel gases

• The Nobel gases have full outer shells and they are found in group 0 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.

The Halogens

• Fluorine, Chlorine, Bromine and Iodine are the Halogens and they all have seven electrons in their outer shell. This is why they are found in group 7 of the periodic table.