Particles in the Atom & Atomic Radius (Cambridge (CIE) AS Chemistry)

²³Na⁺

²⁷Al

¹⁹F^-

 ³²S^2-

One proton has a mass 1840 times greater than one electron.

The charge on an electron is equal and opposite to the charge on a proton.

The difference in charge between electrons and protons is balanced by the neutrons.

Electrons are spread out in shells around the nucleus while protons are concentrated inside the nucleus.

Increases moving down the group

Increases moving down due to the addition of electron shells 

Decreases moving down due to increasing nuclear forces

Rb has the greatest atomic radius

The proton and electron are deflected because they are charged particles.

 The neutrons are undeflected as they have no charge.

The electron is deflected more than the proton because it has less mass.

The particles travel at different speeds

Electrons shells are added moving across the period which increases the nuclear force of attraction

The nuclear charge increases moving across due to increasing atomic number

There is a greater force of attraction between the nucleus and the electrons

The atomic radius decreases across the period 

4

8

2.4 x 10²⁴

4.8 x 10²⁴