The oxygen 2- ion. The oxygen 2- ion gains two electrons and acts like neon.
For a neutral atom to become an ion with a 2 plus charge it must LOSE TWO ELECTRONS.
If an atom loses an electron, it will be positively charged. An example may make this clearer. A neutral carbon atom has 6 protons and 6 electrons. If you take away an electron, you will have 6 protons and 5 electrons, for a total charge of +6 -5 = +1.
Oxygen wants to gain 2 electrons, so its charge would be 2-, because electrons have a negative charge.
The neutral atom of calcium has 20 electrons; the cation Ca2+ has 18 electrons.
If an atom loses 2 electrons, it will have a positive 2 charge when it forms an ion. This is because it loses negatively charged electrons, leaving behind a positively charged atom due to an excess of protons.
Magnesium has 12 protons, so if there are only 10 electrons, then it will have a +2 charge.
An Oxygen atom would never contain 10 electrons on its own. It would have a maximum of 8 electrons at one time, unless the "oxygen atom" you are referring to is in fact an oxygen ION, in which case the charge would be -2. However, an oxygen ion can never be "by itself". It must be bonded with either itself as a diatomic or with another element as a compound.
+10 + (-8) = +2+10 + (-8) = +2+10 + (-8) = +2+10 + (-8) = +2
2 unbalanced electrons have a 2- charge on the molecule/atom
The symbol "24mg2" likely refers to the magnesium ion with a +2 charge. Magnesium has 12 electrons in a neutral atom, but since it has a +2 charge, it has lost 2 electrons, giving it 10 electrons in total when it becomes a Mg2+ ion.
Most atoms are electrically balanced because they have the same number of protons, which have a charge of +1, and electrons, which have a charge of -1. However electrons can be lost or gained. When they are, the atom has a different number of protons to electrons so it becomes charged. Example. An uncharged atom of oxygen has 8 protons and 8 electrons. Sometimes it gains two electrons. This means that it has 8 protons but 10 electrons. +8 -10 = -2. therefore the charged atom of oxygen has a charge of -2.
an ion with a 2- charge has 2 more electrons than usual
For a neutral atom to become an ion with a 2 plus charge it must LOSE TWO ELECTRONS.
Barium has two electrons in its outermost shell, electrons carrying a negative charge. When the Barium atom becomes an ion, these two electrons are lost. Now the Barium atom has more protons than electrons, meaning a net positive charge of 2.
The charge of a calcium atom with 18 electrons will be +2 elementary charges since it has 20 protons and 18 electrons, resulting in a net positive charge. Each elementary charge is approximately 1.602 x 10^-19 Coulombs, so the total charge of the calcium atom would be 2 * 1.602 x 10^-19 Coulombs.
Gained 2 electrons
If the number of protons is the same as the number of electrons, the atom is Neutral (the +'s and the -'s cancel out, leaving no net charge). If there are more electrons than protons, then the atom is negatively charged. If there are more protons than electrons, then the atom is positively charged. A Helium atom has 2 protons and 2 electrons: ++ --: No net charge: Neutral. A Chloride ion has 17 protons and 18 electrons: 17+ 18 -: Net charge -1: Negative (anion). A Sodium ion has 11 protons and 10 elections: 11+ 10-: Net charge +1: Positive (cation.