C1

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Floating topic

C1

C1.2

C1.2.1-Atomic structures

Subtopic

Elements

Substances whose atoms have the same atoms have the same atomic number

Size of atoms

Atomic radii and bond length is typically around 10^-10 (0.1nm)

The length of the bond is the distance between two joined atoms

The size of an atom is given by its atomic radius(half its diameter)

C1.1

C1.1.3-Limitations of the particle model

Forces

Particles are held together by electrostatic forces

Forces of attraction between positive and negative charges

The further the particles the weaker the forces

Space

To calculate ratio of an atom

Ratio= Distance between atoms Diameter of atom

Size

The smallest particle that make up a substance is called an atom

The smallest atoms are helium at 62x10^-12 m in diameter

Distance between two helium is 55x larger than diameter of the atom

C1.1.2-Chemical and physical changes

Chemical change is a change which produces new substances

It usually irreversible and creates a new substance

The particles then form in a different way

Physical changes is a change of state

Reversible and no new substances made

In a physical change the particles are the same but their arrangement and movement change

E.g. Ice melting

C1.1.1-Paritcles

Models are used to solve problems, making predictions and developing scientific knowledge

The particle model is used to describe the arrangement of particles and their different states

The particle model is used to explain certain properties of a substance

Everything is made from matter

Matter is made from paritcles