Chapter 2 AS - Bonding & Structure Flashcards
(20 cards)
Define ‘ionic bonding’.
Strong electrostatic attraction between two oppositely charged ions.
What does the strength of an ionic bond depend on?
1) Sizes of ions
2) Charges of ions
How does the size of an ion affect the strength of the ionic bond formed?
An ion with a greater ionic radius:
- Weaker attraction to oppositely charged ion
- Since the attractive forces have to act over a larger distance
- Weaker ionic bonding
What are ‘isoelectronic species’ ?
Chemical species that have the same number of electrons
How does the charge of an ion affect the strength of the ionic bond formed?
An ion with a greater charge:
- Greater attraction to oppositely charged ion(s)
- Stronger forces of attraction between oppositely charged ions
- Stronger ionic bonding
Define ‘covalent bonding’.
The strong electrostatic attraction between two nuclei and the shared/bonding pair of electrons between them
Why are electrons shared between two outer shells?
To form a full outer shell
How are multiple covalent bonds formed between two atoms?
When multiple electron pairs are shared between them
How many electrons are there in a single covalent bond?
2 electrons
How is the length of a covalent bond linked to its strength?
Shorter bonds are stronger:
- Atoms are held closer together
- Forces of attraction act over a smaller distance
- Electrostatic forces of attraction are stronger
- Requiring more energy to overcome
Compare the strength and size of double and triple bonds to single bonds.
Double bonds and triple bonds are shorter than single bonds.
So, they are much stronger.
How do dative/coordinate bonds form?
When both of the electrons in a shared pair of a covalent bond are donated by a single atom.
How would you indicate the presence of a dative/coordinate bond in a diagram?
Indicated using an arrow from the lone pair of electrons.
What determines the shape of a simple molecule or ion?
The number of bonding electron pairs and lone electron pairs around the central atom and the repulsion between them.
Why do the electrons in electron pairs around the central atom repel each other?
For maximum separation and minimum repulsion, the largest bond angle possible is formed between the covalent bonds.
What effect do the lone pairs have on the shape of the molecule or ion?
Provide additional repulsive forces which changes the bond angle.
By what magnitude does a single lone pair of electrons reduce the bond angle between covalent bonds?
Reduces by 2.5 degrees
Define ‘bond length’.
The average distance between two nuclei in a covalent bond
Define ‘bond angle’.
The angle between two covalent bonds from the same atom
