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What is an Atomic
Number?
Each Chemical element on the Periodic table is given a unique
Atomic Number - a Periodic Table Number.
Atoms are made up of three kinds of smaller particles, called
protons, neutrons and
electrons. The atomic number is the number of protons in the atom,
see Number of Protons and Neutrons.
Atoms must have equal numbers of protons and electrons. The chemical elements of the periodic table are listed in
order of atomic number.
What is an Atomic
Number? What are Protons and Electrons?
Protons and electrons have
different properties. Electrons are tiny, very light particles that have a
negative electrical charge. Protons are much larger and heavier than electrons
and have a positive charge.
What is an Atomic
Number?
In 1913 the English scientist, Henry Moseley, determined the
atomic number of each of the elements and modified the 'Periodic Law'
accordingly. The atomic number of an element is the same as the number of
electrons or protons in that particular atom. Across the Periodic table the
elements are placed in the order of their atomic numbers starting with the
lowest number of 1 which is the atomic number for hydrogen.
What is an Atomic
Number?
The Periodic
Law
The Periodic Law states that the
Physical and Chemical Properties
of the elements recur periodically in a systematic and predictable
way when the elements are arranged in order of increasing atomic number. The
Periodic Table is therefore arranged
in order of increasing atomic numbers
according to the Periodic Law. The Periodic Law can be explained
further by comparing the chemical and physical properties of elements.
What is an Atomic
Number? Periodic Trends
When elements in the Periodic Table are arranged according to
atomic number, elements show repeating, or periodic trends in their chemical and
physical properties.
The Periodic Table can therefore be used by chemists to observe chemical and
physical properties, characteristics, patterns and relationships between over
100 elements in just one chart. So the Atomic Number of an element is very
important. The higher the atomic number, the greater the number of protons in
the nucleus. This means that more neutrons are required to "bind" the nucleus of
the atom together.
What is an Atomic
Number? Every number is unique...
Every element has a unique Element Symbol and a unique Atomic
Number. The
same Atomic Number for each element is used all over the world and instantly
recognised by scientists and chemists. It is imperative for chemistry students
to be able to recognise the names of elements from their Atomic number.
What is an Atomic
Number? Atomic Number Chart
The following chart, or list, details the names of all of the
Periodic Table elements and their corresponding Atomic Number.
List of Elements
and their Atomic Number
List of Elements
and their Atomic Number
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