Periodic table

Atomic Theory

What makes up an atom?
How is the Periodic Table organized?

The Atom

Nucleus:
- The presence of protons and neutrons in the nucleus accounts for all of the atoms mass.
- Has a positive charge because of the protons. Neutrons have no charge.
- The number of protons in each atom is unique to that atom. It is this number of protons in each element that gives it its unique atomic number.
- A hydrogen atom only contains one proton in the nucleus and no neutrons.
- There are more neutrons than protons in heavy atoms to balance out the repulsive forces of the excessive numbers of protons.
- The charge on a nucleus is always positive due to protons positive charge and the lack of charge on neutrons. This charge is the same as the atomic number

Organization of the Periodic table

- Each element is listed according to its atomic number, left to right and then row by row top to bottom.
- Each row is called a period and each column is called a family
- Metals are to the left and the middle whereas the nonmetals are to right of the table
- Metalloids make a border between the metals and non metals
- Elements in the same family or group have similar properties. They are the: (group I) Alkali metals; (group II) Alkali earth metals; (group 17) halogens;(group 18) Noble gasses.
- Reactivity increases from left to right across the table
- Elements from groups three to 12 are the transition metals.

Name three elements in groups I, II, 17, 18 and the transition metals.