Atomic Structure & Bonding
1. Atomic Structure
- The nucleus contains positively charged protons and uncharged neutrons.
- The electron cloud is composed of negatively charged electrons.
In a neutral atom, protons = electrons
Isotopes are two atoms of the same element having a different number of neutrons.
2. The Periodic Table
- Elements in the same column have similar electronic and chemical properties.
- Elements in the same row are similar in size.
3. Atomic Orbitals
An s orbital has a sphere of electron density and is lower in energy than the other orbitals of the same shell
A p orbital has a dumbbell shape and contains a node (no electron density) at the nucleus. It is higher in energy than an nucleus s orbital
4. The First Row
- There is only one orbital in the first shell
- Each shell can hold a maximum of two electrons.
- Therefore, there are two elements in the first row: H and He.
5. The Second Row
Each element in the second row of the periodic table has four p orbitals available to accept additional electrons: one 2s orbital, and three 2p orbitals.
Since each of the four orbitals in the second shell holds two electrons, there is a maximum capacity of eight valence electrons for elements in the second row.
The second row of the periodic table consists of eight elements , obtained by adding electrons to the 2s and three 2p orbitals.
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