Specification Point 1.39:
Write Formulae for Compounds Formed Between the Ions Listed Above
Ionic Compounds: Formed when atoms of metals transfer electrons to atoms of non-metals to form compounds made up of ions.
Formulae for compounds formed between ions
- Metals: They will lose electrons to another atom and become positively charged ions
- Non-Metals: They will gain electrons from another atom to become negatively charged ions
Sodium Chloride, NaCl, has a typical ionic bond
- Sodium is a group 1 metal so will lose one outer electron to another atom to have a full outer shell of electrons
- They will lose an electron to form a positive ion with the charge 1+
Na 2 . 8 . 1 → Na+ 2 . 8
- Chlorine is a Group 7 non-metal so will need to gain an electron to have a full outer shell of electrons
- one electron will be transferred from the outer shell of the sodium atom to the outer shell of the chlorine atom
- Chlorine atom will gain an electron to form a negative ion with charge 1-
Cl 2 . 8 . 7 → Cl– 2 . 8 . 8
Formula of Ionic Compound: NaCl
Magnesium Oxide, MgO, has a typical ionic bond
- Magnesium is a group 2 metal so will lose two outer electrons to another atom to have a full outer shell of electrons
- They will lose two electrons to form a positive ion with the charge 2+
Mg 2 . 8 . 2 → Mg2+ 2 . 8
- Oxygen is a group 6 non-metal so will need to gain two electrons to have a full outer shell of electrons
- Two electrons will be transferred from the outer shell of the Magnesium Atom to the outer shell of the oxygen atom
- Oxygen atom will gain two electrons to form a negative ion with charge 2-
O2 2 . 8 . 7 → O22- 2 . 8 . 8
Formula of Ionic Compound: MgO
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