Structures And Bonding Flashcards
What are ions
Electrically charged particles formed when atoms lose or gain electrons
What do metal atoms form?
Positively charged ions
What do non-metal atoms form?
Negatively charged ions
What are ionic bonds?
Strong electrostatic forces of attraction between oppositely charged ions
Why are electrostatic forces strong?
The bond between positive (+) and negative (-) is strong as they have
High melting and boiling points so a lot of energy is needed to break the bonds
If an atom loses an electron how do you draw it?
Remove one electron from the outer shell
Chuck a bracket around it
Give it a cheeky plus (+) sign next to it
If an atom loses more than one electron how do you draw it?
Remove the electrons from the diagram
Chuck a bracket around it
Write however many electrons lost with a plus (+) sign after it
If an atom gains an electron, how do you draw it?
Add an electron
Chuck a bracket around it
Write a minus (-) sign next to it
If an atom gains more than one electron, how do you draw it?
Add however many electrons
Chuck a bracket around it
Write however many electrons it gained next to it next to a minus sign
Sodium + chlorine > …..
Sodium chloride
Properties of ionic substances (4)
High melting point
Allow electric current
Does not produce a molecule
Dissolves in water
Properties of covalent substances? (2)
Low melting point
No electric current
What is a lattice?
A giant structure
What are electrostatic forces?
They hold oppositely charged ions together
What are covalent bonds?
Strong bond between 2 non metal atoms. It consists of a shared pair of electrons
What covalent bonds can molecules have?
Single
Double covalent bond (O=O)
Triple covalent bond (nitrogen)
Why do covalent bonds have low melting and boiling points?
The intermolecular forces are weak
What is an isotope ?
Atoms with the same amount of protons but different amount of neutrons
What are the relative masses of the 3 main sub atomic particles?
Electron = 1/1840 Proton= 1 Neutron = 1
How do you draw covalent bonds?
Dot and cross diagram
Two interlocking circles with dots for one set of atoms and crosses for the other
Properties of simple molecular substances ?
Low melting and boiling points
Because of
Weak intermolecular forces
They have strong covalent bonds
They don’t conduct electricity
What are the two main types of covalent bonds?
Simple molecules
Giant covalent structures
Example of simple molecular structures?
CO2
What happens when simple molecular structures are heated?
They have strong bonds between atoms and weak intermolecular forces
The intermolecular forces break
What are giant covalent structures?
High melting and boiling points
Many atoms joined together to form a giant lattice
3 main types of macromolecules (giant covalent)?
Diamond
Graphite
Silica
Properties of graphite ? (4)
Has gaps and layers
The layers can slide over eachother of weak intermolecular forces between the layers. This makes them soft
Has free delocalised electrons which allow an electric current to flow
One carbon atom is joined to 3 others
Properties of diamond? (3)
The atoms are bonded together in a rigid network
There
This makes it hard and solid
It does not conduct heat and electricity as
There aren’t any delocalised electrons
Each carbon atom in joined to 4 others
What is graphite used for?
Lubricants
Why do giant covalent structures have high boiling points ?
Strong covalent bonds must be broken
What is silica?
Similar structure to diamond but contains silicon and oxygen instead of carbon atoms
Found in sand
Metallic structure properties?
High melting and boiling points
Positive ions in a sea of pDelocalised electrons so can conduct electricity
Malleable
Strong attraction between ions and delocalised electrons
Properties of giant ionic structures?
High melting points
Strong electrostatic attraction between positive and negative ions
What are the two types of polymers?
Thermosoftening
Thermosetting
What are thermosoftening polymers?
2 and example
Example- polyethene
Soft and melt because forces between chains are weak
Chains do not join together
What are thermosetting polymers?
Example - melanine
Joined together by cross links
Hard and rigid
Do not soften when heated and can’t be re shaped
When can ionic compounds conduct electricity and why?
When they are melted or dissolved in water
Ions are free to move and carry current. They can’t conduct electricity when solid because ions can’t move around in their lattice structure
What are alloys
Mixture of two or more elements
Used to make a metal harder
What are shape memory alloys?
They return to their original shape after being bent
Used in dental braces
Properties of nanoparticles?
Large surface area to volume ratio
Used in
Sunscreens to block ulterviolet light without being visible on skin
New catalysts
New computers
What are fullerenes?
Cages and tubes with different number of carbon atoms
Used in lubricants and as catalysts
Tube fullerenes are called nanotubes
