1.3 Bonding Flashcards
Metallic bonding
The attraction between delocalised outer shell electrons and positive metal ions in a lattice
How are the metal ions arranged
Packed close together in layers in a regular way
What are the metal ions surrounded by
Mobile electrons
What do mobile electrons do
Move freely within structure
What does delocalised mean
Displaced from where it’s expected to be
What does giant mean
A huge structure- consisting of millions and millions of atoms
What does the number of delocalised electrons depend on
How many electrons are lost from each metal atom
What is ionic bonding
The electrostatic attraction between oppositely charged ions in a lattice
Where does ionic bonding occur
Between metals and non metals
What happens in ionic bonding
Electrons are transferred from a metal to a non metal
What is formed as a result of ionic bonding
Positive and negative ions
What do metal atoms do
Lose electrons and become positively charged
What do non metals do
Gain electrons and become negatively charged
What is the charge on a simple ion related to
It’s position in the periodic table
What ion is formed from group 1 elements
+1
What ion is formed from group 2 elements
+2
What ion is formed from group 3 elements
+3
What ion is formed from group 5 elements
-3
What ion is formed from group 6 elements
-2
What ion is formed from group 7 elements
-1
What does boron not do
Form ions (covalently bonds)
Do carbon and silicon usually form ions?
No
What can transition elements do
Form more than one stable ion
What are compound ions
Covalently bonded species carrying a charge
Eg. Hydroxide and carbonate
Covalent bond
Shared pair of electrons
Where does covalent bonding occur
Between atoms of non- metals
What is a pair of electrons which is not bonded called
A lone pair
When is a double bond formed
When 2 pairs of electrons are shared
When is a triple bond formed
When 3 pairs of electrons are shared
What is a non- octet molecule
A molecule where the central atom doesn’t have a noble gas electron arrangement (8 electrons in a full shell)
Coordinate/dative bonding
A covalent bond in which both electrons of the shared pair come from the same atom
The atom that donates the electrons has a…
Lone pair
The atom that accepts the electron pair does not have a full outer shell of electrons. It is…
Electron deficient
How can coordinate bonds be shown
Using an arrow. The arrow points from the atom donating the electrons
What happens once the coordinate bond is formed
It behaves like a normal covalent bond
What 3 things is the shape of a molecule determined by
The total number of electron pairs around the central atom
The number of bonding pairs of electrons
The number of lone pairs of electrons
What can the shape of molecules be predicted by
The electron pair repulsion theory
What does the electron pair repulsion theory state
- pairs of electrons repel each other so they they are as far apart as possible
- lone pairs repel slightly more than bonded pairs because they’re more compact
- the molecule or ion takes up a shape which minimises these repulsions
- each lone pair reduces the bond angle by 2.5 degrees
How to draw a bond in the plain of the paper
A line
How to draw a bond coming out of the paper
A wedge
How to draw a bond going into the paper
A dotted line
What are compound ions
Covalently bonded species carrying a charge
What shape is a molecule with 2 bond pairs and no lone pairs
Linear
What is the bond angle of a linear structure
180
What is the shape of a molecule with 3 bond pairs and 0 lone pairs
Trigonal planar
What is the bond angle of a trigonal planar
120
What is the name of the molecule with 4 bond pairs and 0 lone pairs
Tetrahedral
What is the bond angle of a tetrahedral structure
109.5
What shape is the molecule with 5 bond pairs and 0 lone pairs
Trigonal bipyramidal
What are the bond angles for a trigonal bipyramidal structure
90 and 120
What is the shape of a molecule with 6 bond pairs and no lone pairs
Octahedral
What is the bond angle for an octahedral structure
90
What is the bond angle in an octahedral structure
90
Do bonding pairs of electrons in double/triple bonds repel in the same way
Yes so the shape and bond angle are the same
What is the shape of a molecule with 2 bond pairs and 1 lone pairs
Bent v-shaped
What is the bond angle of a bent v shaped molecule with 1 lone pair
118
What is the shape of the molecule with 3 bond pairs and 1 lone pair
Pyramidal
What is the bond angle of a pyramidal structure
107
What is the shape of the molecule with 2 bond pairs and 2 lone pairs
V shaped
What is the bond angle of a v shaped molecule with 2 lone pairs
104.5
Why is the bond angle smaller for a v shaped molecule with 2 lone pairs than a v shaped molecule with 1 lone pair
More repulsion
What is the shape of a molecule with 3 bond pairs and 2 lone pairs
Trigonal planar
What is the bond angle of a trigonal planar
120
What is the shape of a molecule with 4 bond pairs and 2 lone pairs
Square planar
What is the bond angle in a square planar
90
What happens when an atom forms a coordinate bond
The shape changes as the number of bonding and lone pairs change
Why does the shape of a molecule change when a coordinate bond forms
Bond pairs repel less than lone pairs so bond angle increases slightly
