C1- Atomic structure and C2-Structure & bonding

what is an element?

a substance made of only one type of atom

what is a mixture?

A mixture is a substance made up of two or more different types of atoms or molecules that are not chemically bonded together.

what is a compound?

substance formed when two or more different types of atoms are chemically bonded together

what is an atom?

smallest unit of matter

what is the charge and mass of a proton?

mass= 1 charge= +1

what is the atomic number of an atom?

number of protons in an atom

what is the mass number of an atom?

number of protons + number of neutrons

how do you work out neutrons in an element?

protons - electrons

why are atoms neutrally charged?

as there are the same number of protons and electrons their charges cancel out

how many electrons can go in each shell?

2,8,8,2

how did Dalton describe atoms

as solid spheres

describe the plum pudding model of the atom

a cloud of positive charge with negative electrons embedded throughout it

what did the gold foil experiment prove?

the atoms have dense nuclei with a positive charge

what did Chadwick discover?

the neutron

what did Bohr’s experiment show?

that electrons are in specific shells

approximately how large are atoms?

radius is about 0.1nm

what are Isotopes?

atoms of the same element with the same number of protons but a different number of neutronsh

how is the modern periodic table arranged?

by their atomic number and in groups according to chemical properties

before the discovery of protons, electrons and neutrons how did scientists organise the elements?

by their atomic weight

why did Mendeleev leave gaps in his periodic table?

for elements that had not been discovered yet

what is group 1 called?

noble gases

what is group 7 called?

halogens

what is group 1 called

alkali metals

why are the group 0 elements unreactive?

they have full outer shells so do not need to lose or gain electrons

how does the boiling point of group 0 elements change down the group?

increases down the group

what happens to the electrons in a covalent bond?

they are shared

what two types of substances have covalent bonds?

giant covalent substances and small molecules

how many bonds does each carbon have in each diamond?

4

explain why diamond and silicon dioxide have high melting points?

giant structures, many strong covalent between the atoms, requires a lot of energy to break

explain why most covalent substances do not conduct electricity?

there are no electrons or ions that are free to move and carry charge

explain why graphite can act as a lubricant?

weak forces between layers which are free to slide over each other

what type of substances are methane and water?

small molecules

describe the structure of small molecules?

strong covalent bonds between atoms, weak intermolecular forces holding the molecules together

explain why small molecules have low melting points?

require little energy to break

what is a polymer?

many small molecules, monomers, joined together in a chain to form a large molecule

what are the three types of bond?

covalent, ionic, metallic

what happens to the electrons in an ionic bond?

they are transferred

what type of metals will form ionic bonds

non-metal and metal

what is the charge on elements from group 1 and 2?

group 1: 1+ group 2: 2+

what is the charge on elements from group 6 and 7?

group 6: 2- group 7: 1-

describe the structure and ionic bonding in an ionic compound?

giant ionic lattice held together by strong electrostatic forces of attraction which require a lot of energy to break

describe the structure and bonding in a metal?

layers of positively charged metal ions with delocalised electrons

why are metals good conductors?

delocalised electrons are free to move through the structure and carry charge

what is an alloy?

a mixture of a metal with another element

why are alloys harder than pure metals?

the layers are disrupted and so not able to slide making the alloy harder than a pure metal

why do larger molecules have higher melting points than smaller ones?

intermolecular force strengthens with increased molecular size

what is graphene and what is it used for?

one layer of graphite- electronics and composite materials

what are nanotubes and what are they used for?

electronics, nanotechnology and materials