Structure and bonding Flashcards
What are ions and how are the formed?
Ions are electrically charged particles that are formed when atoms lose or gain electrons.
Why is the structure of an ion similar to a noble gas?
The loss or gain of electrons leaves a full highest energy level.
What happens to metal atoms when they become ions?
Metal atoms lose the electron, or electrons, in their highest energy level and become positively charged ions.
What happens to non-metal atoms when they become ions?
Non-metal atoms gain an electron, or electrons, from another atom to become negatively charged ions.
How can you work out the number of charges on a metal ion? (+1, +2, +3 etc.)
The number of charges on an ion formed by a metal is equal to the group number of the metal.
How would you draw the electronic structure of a sodium ion, 2,8,1?
Get rid of the last one and put it in brackets (wedding bands) and put a + in the top corner, so it becomes (2,8)+
How would you draw the structure of an oxygen ion? 2,6
Add two dots and put it in brackets, with 2- at the top.
How is an ionic compound formed?
When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms, forming ions, forming an ionic compound.
What are the forces of an ionic bond like?
There is a strong electrostatic force of attraction between these oppositely charged ions, called an ionic bond.
What are the elements in group one called?
The alkali metals
What charge do the alkali metals form when they react with non-metals?
Their ions have a single positive charge.
When is a covalent bond formed?
A covalent bond forms when two non-metal atoms share a pair of electrons.
What are the properties of covalent bonds?
Covalent bonds are strong - a lot of energy is needed to break them.
Low melting and boiling points
How can you work out the number of bonds in a covalent bond?
8 minus the group number.
What are the properties of simple molecular substances?
Low melting and boiling points - This is because the weak intermolecular forces break down easily.
Non-conductive - Substances with a simple molecular structure do not conduct electricity. This is because they do not have any free electrons or an overall electric charge.
What are macromolecules?
Macromolecules have giant covalent structures, their atoms are arranged into giant lattices.
What are the properties of diamond?
Diamond is a giant covalent structure.
As a result, diamond is very hard and has a high melting point. It does not conduct electricity.
Why is graphite softer than diamond?
Graphite is soft and slippery because there are only weak intermolecular forces between its layers.
What is a polymer?
A large molecule formed from many smaller molecules called monomers.
What are thermosoftening polymers?
Thermosoftening polymers soften when heated and can be shaped when hot.
The shape will harden when it is cooled, but can be reshaped when heated up again.
Why can thermosoftening polymers be heated and re-shaped?
Because its tangles polymer chains can uncoil and slide past each other.
The polymer has no cross links.
Whats the difference between thermosetting polymers and thermosoftening polymers?
Thermosetting polymers have different properties to thermosoftening polymers. Once moulded, they do not soften when heated and they cannot be reshaped.
Give an example of a thermoset?
Vulcanised rubber which is used to make tyres.
Why can’t thermosetting polymers be re-shaped?
Because its polymer chains are joined together by cross-links, so they cannot slide past each other easily.
