8.1 Atoms and molecules

Wood is made of?

Cellulose

What is an element?

An element is the simplest form of a substance

What is an atom?

The simplest unit of an element

Describe what is an atom.

An atom is the simplest unit of an element that is electrically neutral and is made up of a positively charged nucleus (protons and neutrons) with negatively charged electrons moving around the nucleus

Can atoms be seen?

No, it cannot be seen by the naked eye

What can molecules exist as?

Elements can exist naturally as

atoms,

simple molecules,

giant molecules and

giant crystalline/lattice structures.

What is a molecule

Group of two or more atoms chemically combined together

What is a molecule of an element?

A group of two or more atoms of the same type chemically combined together

What is a molecule of a compound?

A group of two or more atoms of different types chemically combined together

What is an ion?

Atom or group of atoms that carries an electric charge

What are the sub-atomic particles in an atom?

Proton neutron electron

What are the main parts of an atom?

Nucleus electron

What do the electrons do in the atom?

It moves around the nucleus at a high speed

What are the charges of each sub-atomic particle?

Proton → +

Neutron → 0 charge

Electron → -

What is the charge of the nucleus?

positive as it is made of protons and neutrons

What is the atom mostly made up of?

Empty space

New atomic models are needed as?

Models may not be able to explain many properties of an atom so we develop new models in order to get more reliable information

Relative mass of each sub-atomic particle

Proton = 1

Neutron = 1

Electron = 1/1840

What is the charge of an atom? Why?

An atom is electrically neutral - Number of protons and electrons are equal to each other

What are isotopes?

Atoms with different numbers of neutrons.

Are neutrons always equal to the number of protons?

No

What makes up the mass of an atom? Why?

Mostly mass of nucleus.

Electrons are considered negligible (mass) as they are much lighter than protons and neutrons

How do we find out the number of protons in an element?

Atomic number

Can elements have the same number of protons? Why?

No. It changes the physical and chemical properties of an element.

(RECAP!) What are molecules made up of?

It is made up of two or more atoms that are chemically combined

Applications of atoms

Medicine:

1. Used for radiation therapy to cure diseases

2. MRI and X-ray scans

Energy/war:

1. Nuclear power plants (nuclear energy)

2. Atomic bombs (war)