Flashcards in Chapter 2 Deck (37)
What is the atomic number?
The number of protons
Atoms of different elements will have different number of....
What is an isotope?
When there is the same number of protons but different number of neutrons (same atomic number but different mass numbers)
What is ionic bonding?
Atoms loose or gain electrons to form charged particles (ions) which are strongly attracted to each other because of their opposite charges)
How is the structure of an ionic compound described as?
A regular lattice structure
Name some of the properties of ionic compounds
- high melting points
- high boiling points
- can carry electric current when melted
- dissolve easily
Explain the properties of ionic compounds
-High melting and boiling points because of the strong forces of attraction between the ions therefore it takes a large amount of energy to overcome this attraction
- they can carry electric current because when it melts the ions separate and are free to move in the solution so they will carry electric current
When metal atoms become ions what charge do they have?
Positive charges ( they loose electrons)
When non metals become ions what charge do they have?
Negative (they gain electrons)
Work out the formula of this ionic compound:
What is covalent bonding?
When atoms share electrons with other atoms to obtain full outer shells
Give some properties of simple molecular substances
- usually gasses or liquids, sometimes solids
- don't conduct electricity
- low melting + boiling points (intermolecular forces are easily broken)
Give some properties of giant covalent structures
- there are no charged particles
- all the atoms are bonded to each other (strong covalent bonds)
- don't conduct electricity
- e.g diamond & and graphite
Describe the structure of diamond
* each carbon atoms forms 4 covalent bonds
* hardest natural substance
Describe the structure of graphite
* each carbon atom has 3 covalent bonds this creates layers that are free to slide over each other
* graphite is soft and slippery
* weak intermolecular forces between layers
Describe the properties of metals
- free elections that allows the metal to conduct heat and electricity
- strong electrostatic forces of attraction
- layers are able to slide over each other (allows the metal to be bent and shaped)
What are alloys?
When two or more metals are mixed up together
Why are alloys useful?
Different elements have different sized atoms so when another metal is mixed with a pure metal, the new metal atoms will distort the layers of metal atoms, making it more difficult for them to slide over each other therefore alloys are harder
What is the mass number?
The number of protons and neutrons in the atom
What are nanoparticles?
Really tiny particles
What are fullerenes?
Molecules of carbon shaped like hollow balls or closed tubes
Different fullerenes have different number of carbon atoms
Name some uses or nanoparticles
*Large surface area-> new industrial catalysts
*sensors to detect a particular type of molecule
*nanotubes to make stronger, lighter building materials
* deliver jobs where they are needed because fullerenes are absorbed more easily by the body
Describe thermosoftening polymers
- don't have cross-linking between chains
- forces between chains are easy to overcome (easy to melt)
Describe thermosetting polymers
- have crosslinks (holds chains together in a solid structure
- doesn't soften when heated
- strong, hard and rigid
Describe low density (LD) polythene
Made by heating ethene to about 200°C under high pressure
Used for bags and bottles
Describe high density (HD) polyethylene
Made at a lower temperature with a catalyst
Used for water tanks and drainpipes
What is the relative atomic mass (Ar)
It is the same as the mass number
How do you calculate the relative formula mass?
Add up the relative atomic mass
What is the relative formula mass of MgCl2
24 + (35.5 x 2)=95