Answer:
Explanation:
general expression for the ionization energy of any one-electron species.
= z² x ground level energy / n²
z is atomic no , n is energy level .
ground level energy of
H = 1.31 x 10³ kJ/mol
He⁺ = 2² x 1.31 x 10³ kJ/mol = 5.24 x 10³ kJ/mol
Li²⁺ = 3² x 1.31 x 10³ kJ/mol = 1.18 x 10⁴ kJ/mol
b ) the ionization energy of B⁴⁺.
= 5² x 1.31 x 10³ kJ/mol = 32.75 x 10³ kJ/mol
c ) minimum energy required to remove the electron from the n = 3 level of He⁺ per mole
= 5.24 x 10³ / 9 kJ/mol
= 5.82 x 10² kJ/mol
= 5.82 x 10² x 10³ / 6.02 x 10²³ J
.9667 X 10⁻¹⁸ J
= .9667 X 10⁻¹⁸ / 1.6 X 10⁻¹⁹ eV
= 6.042 eV
= 1237.5 / 6.042
= 204.82 nm
=
d )
The untrue statement is that they high melting points.
The covalent compounds are the compounds exhibiting strong intra-molecular bonds. This is due to the tightness of the atoms within the covalent molecules. The force of attraction between the individual molecules in a covalent compound seems to be weak. The covalent compounds exhibit weak intermolecular forces that hold the atoms together due to this they have a low melting point.
Alkaline earth metal are the elements present in II group in the periodic table and are known as 'Metals' and have a charge of +2.
Alkaline earth metals - Be , Mg Ca, Sr , Ba, Ra
Halogens are present in VII A group in the periodic table and are 'Non-metals' and have a charge of -1.
Halogens - F, Cl, Br, I, At
When Alkaline earth metal (metals) combine with Halogens (non-metals) the compound formed will be ionic compound and the formula of the compound will be based on the charges of the element.
When we write the formula of the ionic compound the charges of the elements get criss crossed.
For example - Mg (Alkaline earth metal) have a charge of +2 and Cl (Halogen) have a charge of -1 and when they combine to form the formula their charges get criss crossed and we will get 
or 
When an alkaline earth metal, A, reacts with a halogen, X, the formula of the Ionic compound formed should be 
Answer:
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