Answer:
+2
Explanation:
Alkaline earth metals are present in group 2 of periodic table. There are six elements in second group. Beryllium, magnesium, calcium, strontium, barium and radium.
All have two valance electrons.
Electronic configuration of Beryllium:
Be = [He] 2s²
Electronic configuration of magnesium.
Mg = [Ne] 3s²
Electronic configuration of calcium.
Ca = [Ar] 4s²
Electronic configuration of strontium.
Sr = [Kr] 5s²
Electronic configuration of barium.
Ba = [Xe] 6s²
Electronic configuration of radium.
Ra = [ Rn] 7s²
They are present in group two and have same number of valance electrons (two valance electrons) and show oxidation state +2 by loosing two valance electrons. They also show similar reactivity.
They react with oxygen and form oxide.
2Ba + O₂ → 2BaO
2Mg + O₂ → 2MgO
2Ca + O₂ → 2CaO
this oxide form hydroxide when react with water,
BaO + H₂O → Ba(OH)₂
MgO + H₂O → Mg(OH)₂
CaO + H₂O → Ca(OH)₂
With sulfur,
Mg + S → MgS
Ca + S → CaS
Ba + S → BaS
Answer: gaseous molecules are far apart
Explanation:
One of the states in which matter exists is gas. Gases are made of up molecules that are far apart, travelling randomly and rapidly within the containing vessel.
Hence, they are easy to compress whereby they occupy limited space as the gaseous molecules are closely packed in vessels like cylinders and transported to places where they may be needed.
Answer:
195.199grams
Explanation:
Fluorine has a molar mass of 18.99984 while calcium has a molar mass of calcium is 40.08.
1 mole of calcium fluoride has a mass of 40.08+2×18.99984
=78.0797 grams
if one mole has a mass of 78.0797 grams, then 2.5 moles have:
2.5 moles× 78.0797 grams/mole= 195.1992 grams
Both salt and sugar have radically different properties (both ... known as table salt, is an ionic compound with the chemical formula NaCl, ...
Answer:
Ground state
Explanation:
Ground state is the lowest energy level of particle. In this state toms are stable.
When transition occur from lower energy level to higher energy level require a gain of energy. Electron could not jump into higher energy level without gaining thew energy.
When electron jump into lower energy level from high energy level it loses the energy.
The process is called excitation and de-excitation.
Excitation:
When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits.
De-excitation:
When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum.
