Periods are types of elements.
The periodic table has 7 periods and 18 groups. The periods are in a horizontal line and the groups are in a straight line like up to down.
118 elements are in the periodic table of elements; some of them are still unnamed (January 2013).
The horizontal rows are called periods, there are 7. The vertical rows are groups and there are 18.
These chemical elements are called transition metals.
The elements are arranged in the increasing order of their atomic number and repeating properties.
Because the elements that have similar properties are arranged in groups - or 'periods'.
a Periodic Table organises the different elements, according to the atoms' mass, type, properties, reactivity etc. See the question about: periodic table patterns
7The Periodic Table has 7 periods and 18 groups.
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The periodic table has 7 periods and 18 groups. The periods are in a horizontal line and the groups are in a straight line like up to down.
It is arranged such that similar elements with similar preferred bonding arrangements are aligned vertically. This exposes the various s, p, d, and f bonding orbitals for each successive "exterior" shell, and so appears to repeat... hence "periodic".
118 elements are in the periodic table of elements; some of them are still unnamed (January 2013).
Periods in periodic table refers to rows.Each row element has its specific characteristics.There are 7 rows in a periodic table.
In some periodic tables
the horizontal rows (not groups) are known as periods.
The horizontal rows are called periods, there are 7. The vertical rows are groups and there are 18.
These chemical elements are called transition metals.