| Group | Period |
|---|---|
| - Vertical Column of elements - Consists of 18 groups of elements - Run from Top to bottom | - Horizontal Row of elements - Consists of 7 periods of elements. - Run from Left to right. |
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elements in periodic table → arranged in periodic table in order of proton number (atomic number)
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Vertical columns in periodic table → called Groups and horizontal rows are called Periods
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Elements in periodic table → classified as metals, non-metals, metalloids.
- Metals and non-metals are separated by → Hays McDaniel Line
- Atom of elements in same group have same number of valence electrons
- For elements 13-18 (except helium) → number of valence electrons is the group number minus 10. (E.g. chlorine has 17-10 = 7 valence electrons)
- Atoms of elements in same period have the same number of electron shells
Important
Number of electron shells an element has is the same as its period number
Note
Elements with the same number of valence electrons have similar chemical properties. → as valence electrons are involved in chemical reactions. we can thus deduce → that elements in the same group → have similar chemical properties