Unit 1 - Covalent & Ionic Bonding Flashcards
Why do atoms form bonds?
To achieve a full stable electron arrangement.
(Like noble gases)
They do this by either sharing or transfering electrons.
When are covalent bonds formed?
Formed when elements SHARE Electrons.
What elements USUALLY form to make covalent bonds?
USUALLY formed between NON-METAL elements.
Covalent bonds in elements - diatomic elements
Some non metal elements join together in twos. They share electrons to have full outer shells.
They are Called DIATOMIC ELEMENTS.
What are the diatomic elements
Magic 7
Hydrogen - H2
Nitrogen - N2
Oxygen - O2
(2 should be small at bottom right)
Fluorine - F2
Chlorine - Cl2
Bromine - Br2
Iodine - I2What are diatomic elements?
Some non-metal elements join together in twos. They share electrons to have full outer shells.
Examples
Hydrogen- H2
Nitrogen- N2
Oxygen - O2
(2 should be small at bottom)
Covalent bonds
Atoms share electrons so the atoms are now stable.
Between 2 or more non metal atoms.
A covalent bond is an electrostatic force of Attraction between the positive nuclei and the shared electrons.
What are ions?
An ion is an atom or molecule with a net charge due to the loss or gain of one or more electrons.
How do atoms form bonds?
Atoms form bonds by either sharing or transferring electrons.
What are the shapes of molecules?
Linear molecule
Angular molecule
Trigonal pyramidal
Tetrahedral
Ionic bonds definition
An ionic bond is an electrostatic force of attraction between positive and negative ions.
How are ionic bonds formed?
Ionic bonds are formed when atoms TRANSFER electrons.
Usually a metal and a non metal atom.
What atoms form ionic bonds?
USUALLY metal and non-metal atoms
Non metals atoms gain the electrons (- charges)
Metal atoms lose electrons (+ charges)
Bonding structures (4)
Covalent molecule
Covalent network
Ionic lattice
Metallic lattice
When are ionic bonds formed?
Formed when atoms TRANSFER electrons.
USUALLY formed between metal and non-metal atoms.
Ionic bonds - properties
Always solid at room temperature
high melting and boiling points because of the strong ionic bonds between the ions.
Tend to dissolve in water
Covalent bonds - properties
Can be any state at room temperature
Tend to be insoluble in water
Low boiling and melting points
Poor conductors of heat and electricity
???
Ionic bonds - structure
Lattice structure
Conducts when in a solution and molten.
Covalent bonds - structure
Network structure
- high melting point
Molecule
- low melting point
(Never conducts electricity)
The different types of bonds
- Ionic lattice
- Metallic lattice
- Covalent molecule
- Covalent network
Covalent network- properties
Low melting point ?
Low boiling point ?
Weak intermolecular forces ONLY hold the molecules as solids
NO COVALENT BONDS ARE BROKEN WHEN MELTING OR BOILING
Do not conduct
Usually insoluble in water
Non-metals Very high melting point ??? Very high boiling point Strong and hard Insoluble in water Do not conduct - except for graphite
Ionic bonds structure
Ionic compounds always have giant ionic lattice structures. The ions form a closely packed regular lattice.
There are very strong electrostatic forces of attraction between oppositely charged ions.
Covalent compounds shapes
Linear
Angular
Trigonal pyramidal
Tetrahedral
Covalent molecule - properties
Covalent molecules are small molecules with strong covalent bonds within the molecule but weak intermolecular forces between molecules.
- low melting and boiling points because of the weak intermolecular forces (which are broken easily during these state changes). (*no covalent bonds are broken when melting or boiling)
- this is also why they are GASES at room temperature.
- Cannot conduct electricity because they have no changed particles which are free to move.
- insoluble in WATER
Covalent network - properties
A covalent network is one giant structure made up of very strong covalent bonds.
- VERY high melting and boiling points because they have very strong covalent bonds which would require alot of energy to break.
- CANNOT conduct electricity (except for graphite)
- insoluble due to their large size.
Ionic lattice properties
- high melting and boiling points because they contain strong ionic bonds which must be broken in order to change state (and to break up lattice structure)
- cannot conduct as a solid because the charged particles are not free to move.
- can conduct as a liquid or in solution/molten because their charged particles (ions) are free to move towards oppisitely charged electrodes.
- soluble in water because as they dissolve the lattice structure breaks up so the ions are free to move and be surrounded by water molecules.
What elements form giant covalent network structures?
Carbon in the form of graphite or diamond.
Boron
Silicon
