It has two electronic shell and its highest quantum no is 2
Neon
The period number of an element in the periodic table indicates the highest principal energy level that electrons occupy in an atom. For example, elements in Period 1 have electrons in the first energy level, while those in Period 2 have electrons in the first and second energy levels. Thus, the period number directly reflects the number of electron shells or energy levels present in the atom. Each subsequent period adds an additional energy level.
alpha radiation consists of 2 protons and 2 neutrons. It comes from the nucleus of an atom.
Only nitrogen (but in the period 2) has 7 electrons in the neutral atom.
An example of a covalent compound formed between an element in period 2 and a halogen is hydrogen fluoride (HF). This compound is formed by the sharing of electrons between the hydrogen atom (period 1) and the fluorine atom (halogen).
Atom number 20 is Calcium (period IV, group 2)
The name helium tells that its atomic number is 2, containing 2 protons in each atom. The numerical part of the name shows that each atom also has one neutron.
preggers
Lithium is in the second period. It is an alkali metal. It has 2 rings of electrons.
Atom number 20 is Calcium (period IV, group 2)
if an element has 1 shell in its atom it is in period 1and so on... 2 shells=period 2 3 shells=period 3 4 shells=period 4 5 shells=period 5 6 shells=period 6 7 shells=period 7
This supposition is the basis of the atomic theory, beginning 2 500 years ago.