Atoms and the Periodic table

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Slide 1

Atoms and the Periodic Table.

We can classify (arrange) elements in different ways:-

naturally occurring/made by scientists

solid/liquid/gas

metal/non-metal

Slide 2

The Periodic Table of the Elements.

The Periodic Table lists the chemical elements in increasing

atomic number.

The Periodic Table arranges elements with similar chemical properties in

groups (vertical columns).

All the elements in a group have similar

chemical properties as they have

the same number of outer electrons.

Slide 3

The Periodic Table of the elements is a useful way of classifying the elements.

A vertical column of elements in the periodic table is called a

group.

The elements in the same group of the periodic table have

similar chemical properties.

The noble gases are a group of very

unreactive elements.

Slide 4

Groups of elements have names

Group 1 -

Between groups 2 and 3 -

Group 7 -

Group 0 -

the alkali metals

the transition metals

the halogens

the noble gases

Slide 5

Every element is made up of very small particles called

atoms.

Atoms of different elements have a different number called the

atomic number.

Atoms have a very small, positively charged

nucleus, with negatively charged electrons outside the nucleus in

energy levels.

Slide 6

The nucleus of every atom (except hydrogen) contains two particles:-

Neutrons (no charge / mass 1amu)

In energy levels outside the nucleus we find

Protons (+ve charge / mass 1amu)

Electrons (–ve charge / mass 1/2000amu)

Slide 7

Atoms are neutral because the positive charge of the nucleus is equal to all of the negative charges of the electrons added together.

11 electrons

11 negative charges

11 positive charges

11 protons

Atoms are neutral because the numbers of protons and electrons are equal - the opposite charges cancel.

Slide 8

Nuclide notation – how many protons, neutrons, and electrons in atoms?

37

Mass number

(protons + neutrons)

Cl

17

Atomic number

(number of protons)

–

20

number of neutrons

As atoms have no charge, the number of electrons is the same as the number of protons. This atom has 17 electrons.