Ions Flashcards
What is an ion?
an atom or a group of atoms with a positive or negative charge
What is an anion?
- a negatively charged ion
- formed when an atom or a group of atoms gains one or more electrons
Describe the structure of an ionic compound.
Ionic compounds form a giant ionic lattice where every positive ion is surrounded by/attracted to a negative ion by electrostatic forces.
There are a lot of ionic bonds between the ions.
What is a cation?
- a positively charged ion
- formed when an atom or group of atoms loses one or more electrons
Name the charges that group 1, group 2, group 6 and group 7 ions will always have.
1: +1
2: +2
6: -2
7: -1
Do metal atoms lose or gain electrons?
metal atoms lose electrons becoming positive ions (cations)
Do non-metal atoms gain or lose electrons?
non-metal atoms gain electrons to form negative ions (anions)
Why can’t ionic compounds that are solids conduct electricity?
they have no free moving ions to carry charge
Why can ionic compounds that are liquid or molten carry charge?
they have free moving ions that can carry charge
Why do ionic compounds have high melting and boiling points?
They are held together with electrostatic forces between oppositely charged ions, there are strong ionic bonds between the particles/ions.
The ionic lattice contains a lot of bonds that need to be broken, so a lot of energy is needed to break them, resulting in a high melting/boiling point.
Calculate the number of protons, neutrons and electrons in a sodium ion, ²³₁₁Na⁺.
number of protons = 11
number of neutrons = (23 - 11) = 12
number of electrons = 11 - 1 = 10
Give the formula for the ions formed by atoms of the following elements:
(a) lithium
(b) magnesium
(c) sulfur
(d) bromine
(a) Li⁺
(b) Mg²⁺
(c) S²⁻
(d) Br⁻
Describe the meaning of the term ion.
a charged particle formed when an atom of group of atoms loses or gains electrons
Calculate the number of protons, neutrons and electrons in the following ions:
(a) ⁴⁰₂₀Ca²⁺
(b) ¹⁹₉F⁻
(a)
protons = 20
neutrons = (40 - 20) = 20
electrons = (20 -2) = 18
(b)
protons = 9
neutrons = (19 - 9) = 10
electrons = (9 + 1) = 10
Calcium is an element in group 2.
Fluorine is an element in group 7.
Describe what happens when they react together, and the structure of the salt that is formed afterwards.
Calcium has 2 electrons in its outer shell, and fluorine has 7. Two fluorines will react with one calcium.
When they react together, the two electrons in calciums outer shell will transfer to the fluorine, each fluorine atom will gain one electron.
This causes all three atoms to gain full outer shells.
Calcium loses 2 electrons, so it has a charge of +2.
Fluoride gains 1 electron, so both ions have a charge of -1.
A giant ionic lattice structure is formed.
The negatively charged fluoride ions are attracted to the positively charged calcium ions by electrostatic forces.
The structure will have a high melting and boiling point, because there are a lot of strong ionic bonds between the ions.
This means that a lot of energy is needed to break them, resulting in a high melting/boiling point.
