Periodic Table Notes

1. Periodic Table Notes 8th gr. Physical Science

2. Atomic Number- the number of protons in an atom • The number of protons in an atom is EQUAL to the number of electrons in an atom. So if an atom has an atomic number of 82… There are ______ protons There are ______ electrons

3. Atomic mass number- the sum of the number of protons and neutrons in the nucleus of an atom • Number of neutrons = atomic mass – atomic number • So if the atomic mass is 207 and the atomic number is 82, then there are _______ neutrons in the atom.

4. Modern periodic table- is arranged according to increasing atomic numberand by physical and chemical properties. • As you move from left to right on the PT, the number of protons increases by one.

5. Periods- are the horizontal rows on the table. • The elements increase by one proton and one electron as you move from left to right.

6. Group aka Family- are the vertical columns that sharesimilar chemical and physical properties to one another.

7. Group 1- Alkali metal family • the most reactive metal family and are very reactive in water, soft, silvery grey, have one valence electron and react well with the Halogen family (group 17)

8. Group 17- Halogen Family is the most reactive nonmetal family on the periodic table. • The often form compounds with the Alkali metal family (group 1) • They have 7 valence electrons • Group 18- Noble gases • Do not react to form compounds, they are inert • All but Helium have 8 valence electrons

9. Reactive- the ability to chemically react with another element to form a compound.