A period of elements is a horizontal row on the periodic table.
That some had the same among of Protons and Neutrons. That each coumn had a preiod!
We would find it easier to respond to this question if we knew what is meant by the 'top 20 elements'.
It is a phrase of uniform nature, composed of parts or elements that are all of the same kind
Hydrogen and oxygen. What is probably meant is which two elements make dihydrogen oxide (water; H2O). The answer remains the same: hydrogen and oxygen.
The activity of an element is its ability to react the easier an element reacts with other elements the higher its activity is.
it depends on your body
no
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That some had the same among of Protons and Neutrons. That each coumn had a preiod!
the elements of a poems structure
is the judicial mayor in yhe soanish colonial preiod
"Family of elements" is the synonym of group (column) in the periodic table of Mendeleev.
Dogs come into heat every 6 months.
when a cow ( female elephant ) is pregnant, it is called gestation preiod.
Hazards that affect the average condition of a particular place for a preiod of time
these "formed elements" are called the organelles.
Middle English was spoken throughout part of the Plantagenet era 1154 - 1470