1) Lithium and fluorine:
Ionic charges: lithium cation Li⁺ and fluorine anion F⁻.
Chemical formula LiF.
In ionic salt lithium fluoride (LiF), fluorine has electronegativity approximately χ = 4 and lithium χ = 1 (Δχ = 4 - 1; Δχ = 3).
Fluorine attracts electron and it has negative charge and lithium has positive charge.
2) Beryllium and oxygen:
Ionic charges cation Be²⁺ and anion O²⁻.
Chemical formula is BeO.
Beryllium is metal from group 2 and oxygen is nonmetal from group 16.
Electron configuration of beryllium: ₄Be: 1s² 2s², it has two valence electrons in 2s orbital.
Beryllium lose two electrons and to gain electron configuration as noble gas helium (He).
Electron configuration of oxygen atom: ₈O 1s² 2s² 2p⁴.
Oxygen gain two valence electron to form anion with stable electron configuration as noble gas neon (atomic number 10).
3) Magnesium and fluorine:
Ionic charges cation Mg²⁺ and anion F⁻.
Chemical formula is MgF₂.
Magnesium fluoride (MgF₂) is salt, ionic compound.
Magnesium (Mg) is metal from 2. group of Periodic table of elements and has low ionisation energy and electronegativity, which means it easily lose valence electons (two valence electrons).
Magnesium has atomic number 12, which means it has 12 protons and 12 electrons. It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
Fluorine (F) is nonmetal with greatest electronegativity, which means it easily gain electrons.
Fluorine has atomic number 9, which means it has 9 protons and 9 electrons. It gain one electron to form fluorine anion (F⁻) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
4) Aluminum and chlorine:
Ionic charges cation Al³⁺ and anion Cl⁻.
Chemical formula is AlCl₃.
The right name for AlCl₃ is aluminium chloride.
Aluminium chloride is a salt with ionic bonds.
Aluminium (metal from group 13) has oxidation number +3 and chlorine (nonmetal from group 17) has oxidation number -1, chemical compound has neutral charge (+3 + 3 · (-1) = 0).
5) Beryllium and nitrogen:
Ionic charges cation Be²⁺ and anion N³⁻.
Chemical formula is Be₃N₂.
Atomic number of nitrogen is 7, it has 7 protons and 7 electrons.
Electron configuration of nitrogen atom: ₇N 1s² 2s² 2p³.
Nitrogen gain three electrons to form anion with stable electron configuration as noble gas neon (atomic number 10).
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