structures of matter Flashcards
1
Q
elements
A
- exists as atoms or molecules
- molecule of 1 element = 2 or more atoms chemically combined
- cannot be broken down into simpler substances
2
Q
compounds
A
- 2 or more elements which are chemically combined in fixed ratio
- consists of either molecules or ions
- only broken down through chemical methods
- properties are different from constituent elements
3
Q
mixtures
A
- 2 or more elements / compounds mixed in varying ratio
- can separate through physical methods
- properties are same as constituent elements
4
Q
melting & boiling points
A
- influenced by strength of electrostatic forces of attraction
- ionic compounds with higher charges have higher melting and boiling point
- dependent on molecular size
- large molecules held by stronger forces of attraction
5
Q
simple molecular structures
A
- covalent substances with simple molecular structures have small molecules held together by weak intermolecular forces of attraction
- low melting and boiling points
6
Q
describe a giant molecular structure
A
- covalent substances with giant molecular structure has an extensive network of atoms held together by covalent bonds
- high melting and boiling point
7
Q
diamond
A
- 1 carbon atom bonded to 4 other carbon atoms
- due to rigid structure , it very hard
- -all valence electron is used for covalent bonding so cant conduct electricity
8
Q
graphite
A
- 1 carbon atom bonded to 3 other carbon atoms forming a layer of giant tetrahedral crystal lattice structure
- many layers of it held by weak intermolecular forces of attraction
- layers can slide over one another
- each carbon atom has one free electron since each atom forms 3 covalent bonds = conduct electricity
9
Q
metallic bonding
A
- giant ionic crystal lattice
- lose electrons=delocalised = sea of delocalised negatively charged mobile electrons
- high melting/boiling point as there is strong electrostatic forces of attraction between sea of electrons and lattice of positive metal ions
