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.