Unit 1: Section 3: Bonding Flashcards
Give the ionic formula for Ammonium
(NH)4+
Give the ionic formula for Carbonate
(CO3)2-
Give the ionic formula for Hydroxide
OH-
Give the ionic formula for Nitrate
(NO3)-
Give the ionic formula for Sulfate
(SO4)2-
What holds positive and negative ions together
Electrostatic attraction
What are ionic crystals (structurally)
Giant lattices of ions
Explain the properties and behaviour of ionic compounds
Can conduct electricity when they are molten or dissolved but not when they’re solid (ions are not free to move in a solidified form)
Have high melting points because they are held together by strong electrostatic forces
Tend to dissolve in water - part of water molecules are negatively charged and some parts are positively charged, the water molecules pull the ions from the lattice and causes it to dissolve
What is a molecule
When two or more atoms bond together
What is a single covalent bond
When two atoms share a pair of electrons
What is a giant covalent structure
Type of crystal structure
Huge network of covalently bonded atoms (macromolecular structure)
Which element forms giant covalent structures and why
Carbon
It can form four strong covalent bonds
Explain the structure of an example of a giant covalent structure
Graphite
C atoms are arranged in sheets of flat hexagons covalently bonded with three bonds each
The fourth outer electron of each carbon atom is delocalised
What are the forces that hold together the bonds in a giant covalent structure
van der Waals forces
Explain the properties of graphite
Weak bonds between layers - sheets can slide over each other making it slippery
Delocalised electron means that it can conduct electricity
Layers are far apart compared to length of the covalent bonds so it has low density
Strong covalent bonds so high melting point
Insoluble - covalent bonds are too strong to break
Explain the structure of diamond
Each C atom is bonded to 4 other C atoms
Atoms arrange themselves in a tetrahedral shape (crystal lattice structure)
Explain the properties of diamond
High melting point - sublimes over 3800K
Hard
Vibrations can travel through the stiff lattice so it’s a good conductor of heat
Can’t conduct electricity
Won’t dissolve in any solvent
What are the unshared electrons in a covalent bond called
Lone pairs
What is a charge cloud
The region of negative charge surrounding an atomic nucleus where you have a big chance of finding an electron
Explain Valence Shell Electron Pair Repulsion Theory
Charge clouds repel each other more in lone pairs then bonding pairs
So bond angles are reduced because bonding pairs are pushed together by lone-pair repulsion
What is a co-ordinate bond
One of the atom provides both of the electrons
What is a dative covalent bond
A co-ordinate bond
Give an example of a dative covalent bond
Ammonium
When do dative bonds form
When one atom has a lone pair of electrons, and the other doesn’t have any electrons available to share