1aii: Structure and Bonding - YK Flashcards
What is an ionic bond?
The strong electrostatic force between atoms (non-metal and metal) from a transfer of electrons which forms oppositely charged cations and anions with full outer electron shells
What is an ion?
A charged atom or group of atoms
What charge do ions of atoms from groups 1, 2, 6, and 7 have?
Group 1: +1; Group 2: +2; Group 6: -2; Group 7: -1
How are ionic compounds (salts) named?
If the substance is made of two elements, the compound is ‘metal’ ‘non-metallide’, if there are more, the compound is ‘metal’ ‘non-metallate’ or ‘cation’ ‘anion-ate’
What structure do ionic compounds form?
Lattice (giant structure) of a regular repeating arrangement of ions with alternating charge held together by strong electrostatic forces (ionic bonds)
What are the charges and names of common ions?
Sodium: (Na)+ Lithium: (Li)+ Potassium: (K)+ Ammonium: (NH4)+ Magnesium: (Mg)2+ Calcium: (Ca)2+ Aluminium: (Al)3+ Flouride: (F)- Chloride: (Cl)- Bromide: (Br)- Oxide: (O)2- Sulfide: (S)2- Phosphide: (P)3- Nitrate: (NO3)- Hydroxide: (OH)- Carbonate: (CO3)2- Sulfate: (SO4)2- Sulfite: (SO3)2-
What are some properties of ionic compounds?
High melting and boiling points (strong electrostatic forces take a lot of energy to break)
Conduct electricity when molten or dissolved (charged particles - ions - can’t move in solid
Many are soluble in water
What is a covalent bond?
The attraction between atoms (non-metals) due to shared pairs of electrons giving the atoms full outer shells
What structures do covalent bonds form?
Simple molecules, or molecular compounds, (small distinct groups of atoms joined with covalent bonds) with weak intermolecular attraction
Giant covalent compounds (billions of atoms in a lattice structure)
What is valency?
The valency of an atom is the number of covalent bonds the atom can form (or how many electrons are needed for a full outer shell)
What are some properties of covalent compounds?
Low melting and boiling points (weak intermolecular forces don’t take a lot of energy to break)
Doesn’t conduct electricity (electrons too strongly attracted to nuclei, simple molecules not charged)
Some are soluble in water
(Giant covalent have high mp/bp, insoluble, not conducting except carbon as graphite)
What are polymers and monomers?
Monomers are small, simple molecules that can be joined in chains called polymers (usually linked by covalent bonds between carbon atoms), longer polymers can have more intermolecular forces increasing melting and boiling points
What are some allotropes of carbon an their properties?
Fullerenes: each carbon atom covalently bonded with three other carbon atoms, low melting points (weak intermolecular forces), soft/slippery
Graphene: 1-atom-thick sheet of carbon atoms (can be rolled into a tube), no fixed formula, conducts electricity (has free electrons)
Graphite: giant structure, each carbon atom covalently bonded with three other carbon atoms, high melting point (strong covalent bonds), layered structure (weak forces between layers) makes it a good lubricant, conducts electricity (delocalised electrons not in covalent bonds can carry charge)
Diamond: giant structure, each carbon atom covalently bonded with four other carbon atoms, high melting point (strong covalent bonds), very hard (rigid tetrahedral arrangement)
How are metals bonded?
Outer shell electrons are lost from each individual atom to form a lattice (giant structure) of positive metal ions surrounded by a ‘sea’ of (randomly moving) delocalised electrons
What is metallic bonding?
The bond between positive metal ions and negative delocalised electrons
