Atomic Structure

Recall: An element is a substance which cannot be split into simpler substances by chemical means. Examples??

Atom Atom: An atom is the smallest part of an element (which still keeps the properties of the element)

Structure of an Atom Nucleus Proton Neutron Electron

Proton Protons are found in the nucleus. They have a positive (+) charge.

Neutron Neutrons are found in the nucleus. They have no charge (neutral).

Electron Electrons are found spinning around the nucleus. They move around the nucleus in paths called orbits or shells. They have a negative (-) charge.

Relative Mass A proton has the same mass as a neutron. However a proton has a mass 1,840 times greater than an electron.

Notes…

9 F 18.99 Atomic Number Mass Number

Number of protons in the atom Atomic Number: Number of protons in the atom In a neutral atom, there are always the same number of electrons as protons. Mass Number: Number of protons + number of neutrons

To work out the number of neutrons in an atom... Subtract the atomic number from the mass number Example: 9 F 18.99 Mass No. – Atomic no. = No. of Neutrons 19 - 9 = 10 neutrons