CHAPTER 3 STRUCTURE AND BONDING Flashcards
What type of ions do metals and non metals form and what happens regarding electrons
Metal: Form positive ions + to 4+ and loose electrons
Non metals: Form negative ions - to 4- and gain electrons
What is ionic bonding
Where ionic compounds are held together by strong forces of attraction between their oppositely charged ions.
What is covalent bonding
Its When atoms of non metals share pairs of electrons with each other and form strong bonds. Each shared pair of electrons is a covalent bond. Can be in a simple molecule or giant covalent structure.
Whats a single double and triple covalent bond
It depends on the shared pair of electrons so a single is one shared pair and a double is two shared pairs and so on.
What are intermolecular forces
The forces of attraction between their molecules
Why does diamond have a very high melting point
As it’s a giant covalent structure with many strong bonds holding the atoms into place
Why does nitrogen have strong covalent bond but a very low boiling point
As it has a strong triple bond but the intermolecular forces between the molecules are weak so they are separated easily so it has a very boiling point.
Why does sodium chloride have a high melting point whereas hydrogen chloride is very low
As it’s in a giant ionic structure which forms strong electrostatic forces of attraction in all directions.
Features of simple molecules
- Have low melting and boiling points
- The intermolecular forces are weak
- Have no overall charge so doesn’t carry electrical charge so don’t conduct electricity
What are delocalised electrons and what do they allow
Mobile electrons that move freely along the layers of a substance. They no longer belong to an atom and allow the conduction of electricity and heat.
What are giant covalent structures
Covalently bonded substances with very high melting and boiling points.
Overview of graphite(large covalent structure made of carbon)
Contains layers of covalently bonded carbon atoms with no covalent bonds between the layers, so slide over each over making it soft and slippery. Can conduct electricity and thermal energy due to having delocalised electrons.
Short overview of diamond (giant covalent structure made of carbon
Carbon atoms have a rigid covalent structure so it’s very hard and all outer shell electrons are involved with covalent bonding so can’t conduct electricity.
What is a fullerene and what are they used for and what is its chemical formula
Form of carbon which can form cage like structures and tubes based on hexagonal rings of carbon atoms. Can be used as a transport mechanism for drugs to the body or as reinforcement for composite materials. C60
What is graphene and what will it allow in the future
It’s a single layer of graphite so one atom thick. It has excellent electrical conductivity which will create new developments in the electrons industry in the future.
What is metallic bonding
Positively charged metal ions which are
Held together by electrons from the outermost shell of each metal atom. These delocalised electrons are free to move throughout the giant metallic lattice.
What does a metal consist of regarding metallic bonding
Consists of positively charged metal ions surrounded by a sea of delocalised electrons.
Features of metallic bonding
- Have strong metallic bonds so high melting and boiling points
- The layers can slide over each other so metals can be bent and shaped
- They have delocalised electrons which carry charge and transfer energy which means they are good electrical and thermal energy conductors.
What is an alloy
A mixture of two or more elements at least one of which is a metal
Features of alloys(2)
- They are harder than pure metals as the regular layers in a pure metal are distorted by atoms of different sizes in an alloy
- The different sizes of atoms in an alloy distorts the layers in the structure making it more difficult for the layers to slide over each other.
3 materials that don’t and do conduct electricity
Do: Zinc, Copper, Iron
Don’t: Sugar, wood, Cotton
Features of ionic bonding
- Have strong electrostatic forces of attraction in all directions so have high melting and boiling points
- When melted or dissolved they can conduct electricity as ions are free to move(molten)
What are giant ionic structures
Have oppositely charged ions held together by strong electrostatic forces of attraction acting in all direction in the giant lattice resulting in high melting and boiling points.
How can ionic compounds conduct electricity and when can they do this
When molten of dissolved in water as their ions are now mobile and can carry charge through the liquid.
