ionic compounds Flashcards
(bonding of metals to non metals)
what is an ion
An ion is an atom or molecule that has gained or lost one or more electrons, giving it a charge.
* Cation: A positively charged ion (lost electrons).
* Anion: A negatively charged ion (gained electrons).
* An ionic compound is made up of cations and anions in ratios which produce a neutral substance (no charge).
* They are generally made up of metals and non-metals, and result from a TRANSFER of valence electrons
○ Metals will transfer their outer shell electrons to non-metals
(NOTE: Some ionic compounds do not contain a metal eg. Ammonium chloride (NH4Cl))
How do you represent a cation in nuclide notation?
A cation is a positively charged ion, meaning it has lost electrons.
Example: Sodium (Na) forms Na⁺ (a cation).
Nuclide notation for Na⁺:
((^23)(1)Na⁺)
23 is the mass number (23 protons + 10 neutrons in sodium).
1 is the atomic number (number of protons in sodium).
+ is the charge, indicating it has lost 1 electron.
How do you represent an anion in nuclide notation?
An anion is a negatively charged ion, meaning it has gained electrons.
Example: Chlorine (Cl) forms Cl⁻ (an anion).
Nuclide notation for Cl⁻:
((^35)(1)Cl⁻)
35 is the mass number (35 protons + 18 neutrons in chlorine).
17 is the atomic number (number of protons in chlorine).
- is the charge, indicating it has gained 1 electron.
How do elements in Groups I to VIII form ions?
elements in Groups I to VIII form ions by gaining or losing electrons to achieve a stable electron configuration, often similar to the nearest noble gas. The charge of the ion depends on the number of electrons an element gains or loses to fill or empty its outer shell. (
(The number of valence eletrons can be found by the group and elements found in group 15, 16, 17 all gain eletrons while group 18 doesn’t gain or lose eletrons due to having a full outershell.)
What is a monoatomic ion?
A monoatomic ion is an ion that consists of only one atom. It can be either a cation (positive charge) or an anion (negative charge), formed when an atom loses or gains electrons.
Example:
Na⁺ (Sodium cation)
Cl⁻ (Chlorine anion)
What is a polyatomic ion?
A polyatomic ion is an ion that consists of more than one atom that are bonded together, carrying an overall charge. These ions are formed when a group of atoms, usually non-metals, lose or gain electrons.
Example:
OH⁻ (Hydroxide ion, made of oxygen and hydrogen atoms)
CO₃²⁻ (Carbonate ion, made of carbon and oxygen atoms)
What is an ionic compound?
An ionic compound is a chemical compound formed by the transfer of electrons between a metal and a non-metal. This transfer results in the formation of oppositely charged ions, which are held together by electrostatic attraction (ionic bonds).
How is an ionic compound formed between a metal and a non-metal?
Metal atom loses electrons: The metal atom (which has few valence electrons) loses one or more electrons to become a positively charged ion (cation).
Example: Sodium (Na) loses one electron to form Na⁺.
Non-metal atom gains electrons: The non-metal atom (which has more valence electrons) gains the electrons that the metal lost, becoming a negatively charged ion (anion).
Example: Chlorine (Cl) gains one electron to form Cl⁻.
Formation of the ionic bond: The oppositely charged ions (Na⁺ and Cl⁻) are attracted to each other by the strong electrostatic force (ionic bond), forming an ionic compound.
Result: Sodium chloride (NaCl) is formed, where the ratio of Na⁺ to Cl⁻ is 1:1.
How are the ions held together in an ionic compound?
- The positive ions (cations) and the negative ions (anions) have opposite charges.
- Electrostatic attraction is the force that pulls the ions together: positive attracts negative.
- The ions are arranged in a regular, repeating pattern called a lattice structure, where each ion is surrounded by ions of the opposite charge.
Why is the ionic bond strong?
- The strong electrostatic attraction between the oppositely charged ions creates a stable structure.
- The lattice arrangement maximizes the attraction between ions, making the ionic bond strong and the compound hard to break apart.
How do you predict the charge on a transition metal ion or unknown
to predict the charge on a transition metal ion or an unknown ion, you need to use the following steps:
- Identify the charge of the non-metal (anion) in the ionic compound.
- Balance the charges: Since ionic compounds are neutral, the total positive charge (from the metal ion) must equal the total negative charge (from the non-metal ion).
- Calculate the charge on the metal ion by ensuring that the total charges are balanced.
Common Properties of Ionic Compounds
Ionic compounds typically have the following properties due to the strong electrostatic forces between the ions:
Brittleness
Hardness
High melting point
Electrical conductivity (difference in solid and liquid states)
Why are ionic compounds brittle?
Ionic compounds are brittle because their ions are arranged in a rigid, crystalline lattice structure.
When an external force is applied, the layers of ions may shift, causing ions of the same charge to align. Since like charges repel, this shift causes the compound to break apart along the plane where like-charged ions are aligned, leading to fracturing.
Example: Salt (NaCl) is brittle and breaks easily when hit with a hammer.
Why are ionic compounds hard?
- Ionic compounds are hard because of the strong electrostatic forces of attraction between the oppositely charged ions. These strong bonds hold the ions tightly in place, making the compound resistant to deformation.
- The ions are locked in a fixed, rigid lattice, which makes it hard for the ions to move or slide past each other, contributing to their hardness.
- Example: Magnesium oxide (MgO) is hard due to the strong ionic bonds between Mg²⁺ and O²⁻ ions.
Why do ionic compounds have a high melting point?
- Ionic compounds have a high melting point because of the strong electrostatic forces holding the ions together in the lattice.
- To melt an ionic compound, these strong bonds must be overcome by adding a large amount of heat energy, which leads to a high melting point.
- Example: Sodium chloride (NaCl) melts at about 800°C due to the strong ionic bonds between Na⁺ and Cl⁻.
Why do ionic compounds have different electrical conductivity in solid and liquid states?
- Solid state: Ionic compounds do not conduct electricity in their solid form because the ions are fixed in place in the lattice structure and cannot move to carry an electric current.
- Liquid state (molten): Ionic compounds conduct electricity in the liquid state (or when dissolved in water) because the ions are no longer held in place and can move freely to carry the electric charge.
- Example: Sodium chloride (NaCl) does not conduct electricity when solid, but in molten form or dissolved in water, it does conduct electricity.
Properties of Ionic Compounds
- Brittleness: Ionic compounds are brittle because shifting layers of ions cause like charges to align and repel, breaking the compound.
- Hardness: The strong electrostatic forces between ions make ionic compounds hard.
- High melting point: Ionic compounds have high melting points due to the strong electrostatic forces requiring a large amount of energy to break.
- Electrical conductivity: Ionic compounds do not conduct electricity in solid form because ions are fixed, but they do conduct electricity in molten form or when dissolved in water, as ions are free to move
Crystal Lattice Structure
- Ions are arranged in fixed positions in a three dimensional crystal lattice structure
- The lattice is held together by the attraction (electrostatic force) between the cations and anions. This attraction is called an ionic bond.
- the cations and anions are held in place and not free flowing.
Common Uses of Ionic Compounds
Ionic compounds have a variety of uses due to their properties like high melting points, brittleness, and electrical conductivity in molten or aqueous states. Some common uses include:
- Table Salt (Sodium Chloride, NaCl)
- Fertilizers (Ammonium Nitrate, NH₄NO₃)
- Cleaning Products (Sodium Carbonate, Na₂CO₃)
- Batteries (Lithium Cobalt Oxide, LiCoO₂)
- Plaster and Cement (Calcium Sulfate, CaSO₄)
- Antacid (Magnesium Hydroxide, Mg(OH)₂)
What are solubility rules?
Solubility rules are general guidelines that help predict whether an ionic compound will dissolve (be soluble) or not in water. These rules are based on the charge and size of ions and their interactions with water molecules.
ionic stature
Ionic - cations and anions in a three dimensional lattice, held together by strong ionic bonds
