valence electron

1. THE CHEMICAL
CONNECTION

2. THE LEWIS ELECTRON DOT STRUCTURE
•A Lewis Structure is a very simplified
representation of the valence shell electrons in
a molecule. It is used to show how the
electrons are arranged around individual atoms
in a molecule. Electrons are shown as "dots" or
for bonding electrons as a line between the two
atoms.

3. •Gilbert Lewis was an American physical chemist
whose concept of electron pairs led to modern
theories of chemical bonding. He was able to
formulate a system in which atoms combine to
achieve a more stable electron configuration
after the development of periodic table.

4. •The outer region of the atoms are the ones in
contact in chemical bond. A single electron or
two or more electrons in the outermost energy
level of an atom is called the valence electron.
•The valence electron is the one responsible for
chemical properties of the atom.

5. •Gilbert lewis was an American chemist who
devised a system of dots called the lewis
electron dot structure. This system uses the
symbol of an element and one dot to represent
each valence electron.
•The number of valence electrons is important in
determining the number of bonds an atom will
form, the number of unpaired electrons, and an
atom;s formal change.

6. • The group number indicates the number of electrons
in an element’s outermost energy shell. Also, the
period number indicates the number of shell of an
element.
• For example, all the elements in group 1A (1) have one
velence electron. Moreover, all the elements in group
2A have 2 velence electrons. The same rules applies to
group 3A (13), 4A(14), 5A(15), 6A(16) and 7A(17)or
the representative elements.
• During chemical bonding, an atom needs to attain

8. ELECTRON AFFINITY AND
ELECTRONEGATIVITY
Electronegativity refers to the ability of the atoms to
attract electrons from the other elements.
Electron affinity refers to the amount of energy that is
liberated whenever a molecule or a neutral atom
tends to acquire an electron from the other elements.
It is applied only to a single atom

9. •During chemical bonding, the electrons in the
outermost energy level of atoms interact with
other electrons of other atoms. The ability to
accept one or more electrons is another property
that greatly influences the chemical behaviour of
atoms. This called electron affinity .
•If the electron affinity of an atoms is more
positive, then the element has a greater tendency
to accept electrons.

12. ELECTRONEGATIVITY
•Electronegativity is the ability of an atom to
attract electrons with molecules (bonded
atoms) rather than a free electron.
•In the periodic table, the electronegativity of an
atom generally increases from left to right
across periods, and increases bottom to top (or
decreases as you go down) in groups.

14. • Both electron affinity and electronegativity play an
important role in the chemical bonding properties of
elements.
• Linus Pauling introduced the concept of
electronegativity and created the electronegativity
chart value where the elements on the top right side
of the periodic table are more electronegative.
• Element belonging to group 1A and 2A are less
electronegative elements. This means that fluorine (F)
has the highest ability to attract more electrons when
bonded . The difference in the electronegativity of the

15. •“like electrons, people have a tendency to
lose things or gain things from another as
a result of their bonding and interaction
to satisfy their needs.”