Neutrons are electrically neutral fundamental particles of matter. They are
found in all atomic nuclei except for the hydrogen atom. The nucleus of the
hydrogen atom does not have any neutrons.
The mass of a neutron is approximately 1 amu .
All the elements in Group VIIIA of the periodic table.
Nonmetals can be found in nature in the uncombined elemental form. They are
also found combined with metals, and other nonmetals
to form compounds. The nonmetals are:
- H, He, C, N, O, F, Ne, P, S, Cl, Ar, Se, Br, Kr, I, Xe, Rn
These are the group of elements that are to the right of the diagonal
line on the periodic table.
Nonpolar covalent bond
A type of covalent bond formed by equal sharing of electrons between
two identical nonmetals whose electronegativities
are the identical.
This is a rule stating that bonded atoms tend to possess or share a total
of eight valence electrons.
A process in which electrons are "lost" and the oxidation state of some atom
increases. Oxidation can occur only in combination with reduction.
The balanced half-reaction that is written to show the loss of electrons that
occurs during oxidation.
In the oxidation half-reaction, the electron(s) appears on the right-hand-side
of the reaction. The oxidation state of zinc increases from zero to
+2 corresponding to a loss of two electrons by each zinc atom. Zinc
- An example of an oxidation half-reaction is
|Zn (s) -> Zn+2(aq) + 2 e-
Oxidation number is a number that is assigned to each kind of atom in a compound,
an ion, or an element by using a set of rules.
The reactant that accepts electron(s) and becomes reduced when another substance
Period of elements
A period is a horizontal row in the periodic table.
When elements are arranged in order of increasing atomic number, there is
a periodic variation in the physical and chemical properties of elements.
pH is a measure of acidity or H+ concentration of a solution. Mathematically,
pH = - log [H+]
where, [H+] is the concentration of H+ of the solution
in unit of molarity.
The lower the pH, the more acidic the solution.
A change that does not involve changing any substances into any other substances
is called a physical change. Some physical changes are: boiling water, grinding
sugar into a fine powder, melting wax.
This is a characteristic that a substance can display without undergoing a
change in its identity.
All matter exists in three physical states: solid, liquid, or gas. Although
their physical appearances of these three states are different, their chemical
makeup in all three states are the same.
pOH is a measure of basicity or OH- concentration of a solution.
pOH = - log [OH-]
where, [OH-] is the concentration of OH- of the
solution in unit of molarity.
The lower the pOH, the more basic the solution.
See polar covalent bond.
Polar covalent bond
Also known as polar bond. It is a type of covalent
bond formed by the unequal sharing of electrons between atoms whose
This is stored energy that an object has by virtue of its position. Chemicals
also possess potential energy. This energy is stored in chemicals that can
be liberated during chemical reactions. There are different forms of potential
energy. For example:
- potential energy due to gravity,
- potential energy stored in a spring,
- potential energy due to chemical bonding.
A precipitate is an insoluble or nearly insoluble solid that separates out
of solution as a result of a chemical reaction. The formation of a precipitate
is the driving force for a double replacement reaction.
Precision indicates the reproducibility of a measurement. That is, the closeness
in agreement among the values when the same quantity is measured several times.
Principal energy level
Electrons in an atom occupy specific energy levels that increase in energy
as they increase in distance from the nucleus. These energy levels, designated
by n where n = 1,2,3,...7, are called principal energy levels.
Protons are positively charged fundamental particles. They are found in the
nuclei of all atoms. The number of protons determines the identity of an element.
The mass of a proton is approximately 1 amu .
The spontaneous reactions that take place in the nucleus of the atom which
usually results in the nucleus of the atom to change in composition and the
emission of particles such as alpha and beta particles and gamma rays.
The reactant that donates the electron(s) and becomes oxidized when another
substance is reduced.
A process in which electrons are "gained" and the oxidation state of some
atom decreases. Reduction can only occur in combination with oxidation.
The balanced half-reaction that is written to show the gain of electrons that
occurs during reduction.
In the reduction half-reaction, the electron(s) appears on the left-hand-side
of the reaction. The oxidation state of copper decreases from +2 to
zero corresponding to the gain of two electrons by each Cu2+ ion.
Cu+2 is reduced.
- An example of a reduction half-reaction is
|Cu+2(aq) + 2 e- Cu(s)
All the 'A' group elements in the periodic table.