This document discusses atomic structure and bonding. It begins by explaining electron states using notation like 1s, 2p, 3d. The energy of an electron depends on its state and interactions with other electrons. Valence electrons in the outer shell are important for chemical reactivity. Atoms gain, lose, or share electrons to achieve stable noble gas configurations through ionic bonding between metals and nonmetals or covalent bonding between less electronegative elements. The two main types of chemical bonding are ionic, involving transfer of electrons, and covalent, involving sharing of electron pairs.

1. CHEMISTRY
ATOMIC SRUCTURE AND
BONDING
Short video tutorial series

2.  • So … what are the possible combinations of states?
 • Notation
 n L
 1 K 0 s
 2 L 1 p
 3 M 2 d
 4 N 3 f
 • We can describe an electron state as 1s or 3p or 5f
 Energy levels of the electron states
 • the energy of an electron is determined by its state
 • If there is only one electron in the atom, the
energy depends on n alone
 • If there are more electrons, they interact (repel each
other), and so different states have different energies

3. valence
 The electrons in the outer shell (largest n) are
called
 valence electrons
 Very important for chemical reactions and
holding matter together
 If the outer shell is filled, the atom is inert
 If not, there is a tendency for the outer shell to
become filled
 Electronegative – if it is almost full, the atom has
a tendency to gain enough electrons to fill the
shell
 Electropositive – if it is almost empty, it easily
losses the electrons in the outer shell

4. Valence and chemical reactivity
 Noble gases: s2p6 configuration
 Ne: 1s22s2p6
 Electronegative – if it is almost full, the atom has
a tendency to gain enough electrons to fill the
shell
 Cl: 1s22s2p63s2p5 or [Ne] 3s2p5
 Cl + 1e = Cl- negative ion (anion)
 Electropositive – if it is almost empty, it easily
losses the electrons in the outer shell (typically
metals)
 K: 1s22s2p63s2p64s1 or [Ar] 4s
 K – 1e = K+ positive ion (cation)

5. Types of chemical bonding
2 main types of chemical combination
 Ionic (or electrovalent combination)
 Covalent which is classed into 2
 Ordinary covalent
 Coordinate covalent

6. Ionic bonding
 Typically between highly electropositive
(metallic) and electronegative (nonmetallic)
elements
 NaCl
 Na 1s22s2p63s Cl 1s22s2p63s2p5
Na+ 1s22s2p6 Cl- 1s22s2p63s2p6

8. Covalent bonding
 Takes place between elements with small
difference in electronegativity
 - F, O, N, Cl, H, C, Si…
 s and p electrons are commonly shared to
attain noble gas electron configuration
 Multiple bonds can be formed by one atom
 Eg in H molecule
 2 H: 1s → H2 1s2
 H· + H· →H : H (electron –pair covalent
bond)

9. • O 2s22p4
• N 2s22p3

10. Other binding forces
 Metallic bond
 Van der waal’s
 Hydrogen bonds