Donnez le nombre de protons et d'électrons de chacun des...

Donnez le nombre de protons et d'électrons de chacun des ions suivants: $\mathrm{Na}^{+}, \mathrm{Ca}^{2+}, \mathrm{Al}^{3+}, \mathrm{Fe}^{2+}, \mathrm{I}^{-}, \mathrm{F}^{-}$, $\mathrm{S}^{2-}, \mathrm{O}^{2-}, \mathrm{N}^{3-}$.

Key Concepts

Atomic Number

The atomic number of an element represents the number of protons found in the nucleus of its atoms. This number uniquely identifies the element and forms the basis for understanding its electron configuration and chemical properties.

Ionic Charge and Ionization

An ion is formed when an atom gains or loses electrons, resulting in a net electrical charge. The ionic charge indicates whether an atom has more electrons than protons (negative ion) or fewer electrons than protons (positive ion), and directly affects the chemical behavior of the ion.

Calculating Electron Count in Ions

For a neutral atom, the number of electrons equals the atomic number. When the atom becomes an ion, the electron count is adjusted according to the ionic charge; electrons are removed to form a cation or added to form an anion. The formula involves adding the absolute value of the negative charge to the atomic number for anions or subtracting the positive charge from the atomic number for cations.

Transcript

00:01 So the first thing in determining the number of protons and electrons in an ion is to, excuse me, to find the atomic number for the corresponding element.

00:14 So sodium is number 11, calcium is number 20, aluminum is number 13, iron is number 26, iodine is number 53.

00:32 Three, fluorine is number nine, sulfur is 16, oxygen is number eight, and nitrogen is number seven.

00:50 So you find the element on the periodic table, and your answer here is going to be based on the atomic number, because the number of protons corresponds to the element symbol.

01:04 So you're using the na to look it up on the periodic table, and the number of protons is 11.

01:13 And likewise, for ca, there are the atomic number is 20.

01:18 That's 20 protons.

01:20 13 in aluminum, 26 in iron, 53 in iodine.

01:29 9 in fluorine, 16 in sulfur, 8 in oxygen, and 7 in nitrogen.

01:40 And so the number of protons is equal to the atomic number.

01:45 Now, if i had 11 electrons, then this would be neutral, but it has a 1 plus charge.

01:51 That means that there's one more proton than there is electrons.

01:55 There are 10 electrons.

01:58 And so 10 plus, i'm sorry, 11 plus 10 minus gives us a plus 1 charge.

02:06 And in the case of calcium, it's 2 plus.

02:11 And so we've got 18 negatives and 20 positives.