valence electrons
The number of valence electrons in an atom is the most important factor in
determining how an element will react. Valence electrons, which are found in an atom’s
outermost energy level, are involved in forming chemical bonds.
octet rule
The octet rule states that atoms will lose, gain, or share electrons to obtain a stable
electron configuration of eight valence electrons. In other words, if an atom needs to
become stable, it will react with another atom, which can result in the formation of a
chemical compound.
Covalent compounds
Covalent compounds are formed when two nonmetals or metalloids share electrons.
Ionic compounds
Ionic compounds are formed when electrons are transferred from a metal (which loses
one or more electrons) to a nonmetal (which gains one or more electrons).
cation
A cation is an ion with a net positive charge.
anion
When a nonmetal such as chlorine reacts to become stable, it gains a valence electron.
At first, it is a neutral atom with 17 protons and 17 electrons. When it gains an electron,
the number of protons does not change, and the atom has 17 protons and 18 electrons.
Because there is one more negatively charged electron, an anion forms. An anion is an
ion with a net negative charge.
What happens when an atom loses electrons?
, When an atom loses electrons, it has a net positive charge. After the loss, there are
more protons than electrons, which means there are more positively charged particles.
What happens when an atom gains electrons?
When an atom gains electrons, it has a net negative charge because it gains negatively
charged particle
What is a ionic compound?
An ionic compound is composed of a cation and an anion. An ionic
bond is formed from the cation’s attraction to the oppositely charged
anion.
covalent bond
When a nonmetal atom reacts with a nonmetal or metalloid, the atoms share electrons
to obtain eight valence electrons each. An example can be seen in the model below.
Both the Bohr models and the electron dot structures of the fluorine atoms show their
seven valence electrons. After each atom shares an electron with the other, shown by
the arrows, a covalent bond forms
List the types of covalent bond
single covalent bonds, double bonds, triple bonds
electronegativity
the tendency of an atom to attract shared electrons in a covalent bond. It is a measure
of how hard an atom is pulling on shared electrons. Electronegativity increases going
from left to right in the periodic table.
nonpolar covalent
Atoms share electrons equally, the bond is classified as nonpolar covalent. This
occurs if the two atoms have similar electronegativities, which means that neither atom
pulls significantly harder on the shared electrons than the other.
polar covalent