Bonding and Structure Flashcards
Describe the properties of ionic compounds.
Ionic compounds are usually solids at room temperature.
They have high melting and boiling points.
They are brittle and break easily when force is applied.
Ionic compounds conduct electricity when molten or dissolved in water but not as solids.
Explain why ionic compounds have high melting points and high boiling points.
Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions.
A lot of energy is needed to break these strong bonds, leading to high melting and boiling points.
Explain why ionic compounds conduct electricity when they are molten and in aqueous solution.
When molten or dissolved in water, the ions are free to move.
These mobile ions can carry an electric charge, allowing the compound to conduct electricity.
Explain why ionic compounds do not conduct electricity as solids.
In the solid state, the ions are in fixed positions and cannot move.
Without mobile charged particles, electricity cannot be conducted.
Identify ionic compounds from data about their properties.
Ionic compounds typically have:
High melting and boiling points
Conduct electricity when molten or in solution, but not as solids
Usually dissolve in water
Recall the formulae of simple ions.
Sodium ion: Na⁺
Chloride ion: Cl⁻
Magnesium ion: Mg²⁺
Oxide ion: O²⁻
Calcium ion: Ca²⁺
Explain how cations and anions are formed.
Cations (positive ions) are formed when an atom loses electrons.
Anions (negative ions) are formed when an atom gains electrons.
Use dot and cross diagrams to explain how ionic bonds are formed.
In ionic bonding, metals lose electrons to become cations (positive ions), and non-metals gain those electrons to become anions (negative ions).
Dot and cross diagrams show the transfer of electrons between atoms.
Example: In sodium chloride (NaCl), a sodium atom loses one electron to form Na⁺, and a chlorine atom gains this electron to form Cl⁻.
Explain the difference between an atom and an ion.
An atom is neutral, with equal numbers of protons and electrons.
An ion has a charge because it has either lost or gained electrons.
Cations are positively charged (fewer electrons than protons).
Anions are negatively charged (more electrons than protons).
Calculate the numbers of protons, neutrons, and electrons in simple ions.
Example for Na⁺:
Protons: 11 (atomic number of sodium)
Neutrons: 12 (23-11, where 23 is the mass number)
Electrons: 10 (since Na⁺ has lost 1 electron)
Example for O²⁻:
Protons: 8 (atomic number of oxygen)
Neutrons: 8 (16-8, where 16 is the mass number)
Electrons: 10 (since O²⁻ has gained 2 electrons)
Explain the formation of ions in groups 1, 2, 6, and 7 of the periodic table.
Group 1: Elements lose 1 electron to form 1+ cations (e.g., Na⁺).
Group 2: Elements lose 2 electrons to form 2+ cations (e.g., Mg²⁺).
Group 6: Elements gain 2 electrons to form 2- anions (e.g., O²⁻).
Group 7: Elements gain 1 electron to form 1- anions (e.g., Cl⁻).
Recall the formulae of common polyatomic ions, and the charges on them.
Hydroxide: OH⁻
Nitrate: NO₃⁻
Sulfate: SO₄²⁻
Carbonate: CO₃²⁻
Ammonium: NH₄⁺
Interpret the use of –ide and –ate endings in the names of compounds.
-ide is used for compounds containing only two elements (e.g., sodium chloride, NaCl).
-ate is used for compounds containing three or more elements, one of which is oxygen (e.g., sodium sulfate, Na₂SO₄).
Name ionic compounds using –ide and –ate endings.
Example with -ide: NaCl is sodium chloride.
Example with -ate: Na₂SO₄ is sodium sulfate.
Work out the formula of an ionic compound from the formulae of its ions.
The overall charge of the compound must be neutral.
Example: Mg²⁺ and Cl⁻
1 Mg²⁺ ion requires 2 Cl⁻ ions for neutrality, so the formula is MgCl₂.
