EL5 The Molecules Of Life Flashcards
How do some light elements achieve stability?
By reaching the helium configuration of two outer shell electrons.
How do elements achieve eight outer shell electrons?
By losing or gaining electrons.
Why don’t non-metallic elements form ions?
It’s not energetically favourable.
What is covalent bonding?
The sharing of electrons.
What elements covalently bond?
Non metals.
What does a dot and cross diagram show in covalent bonding?
How sharing electrons gives the atoms more stable electron structures.
What are bonding pairs?
Electron pairs that form bonds.
What are lone pairs?
Pairs of electrons that are not involved in bonding.
What is a double bond?
Where two pairs of electrons form a covalent bond.
What is a triple bond?
Where three pairs of electrons form a covalent bond.
What are dot and cross diagrams useful for representing?
Individual electrons in a chemical bond.
What can we also use to represent bonds?
Lines.
What is a dative bond?
A covalent bond where both electrons come from the same atom.
How is dative bonding shown?
By an arrow pointing away from the atom that donates the electrons.
What is strong within simple covalent molecules?
The covalent intramolecular bonds.
What are weak within simple covalent molecules?
The electrostatic attractions.
What do the weak electrostatic attractions mean?
Small amounts of energy are needed to separate one molecule from another.
What do elements and compounds with a simple molecular structure have?
Low melting and boiling points.
What do simple covalent molecules not do?
Conduct electricity.
What makes a covalent molecules shape?
Electron pair repulsion.
How do groups of electrons arrange themselves?
As far apart as possible.
Why do groups of electrons arrange themselves as far apart as possible?
Because similar charges repel.
What bond angle is a tetrahedral shape?
109.5
What molecules have a tetrahedral shape?
All carbon atoms that are surrounded by four single bonds.
What groups of electrons repel the strongest?
Lone pairs of electrons.
What is the bond angle for a pyramidal shape?
107
What is the bond angle for a bent shape?
104.5
What is a tetrahedral shaped molecule example?
Methane.
What is a pyramidal shaped molecule example?
Ammonia.
What is a bent shaped molecule example?
Water.
How many groups of electrons are there in linear shaped molecules?
2
What is the bond angle for a linear shaped molecule?
180
How many groups of electrons are there in a planar shaped molecule?
3
What is the bond angle for a planar shaped molecule?
120
How many groups of electrons are there in a trigonal bipyramidal shaped molecule?
5
What are the bond angles in a trigonometry bipyramidal shaped molecule?
90 and 120.
How many groups of electrons are there in a octahedral shaped molecule?
6
What is the bond angle in an octahedral shaped molecule?
90
