atomic structure and the periodic table Flashcards
what are atoms made out of
smaller particles and has the basic structure of a nucleus containing neutrons and protons and surrounding shells containing electrons
what is the relative mass of protons, neutrons and electrons
protons and neutrons = relative mass of 1
electrons = very very small sometimes referred to as 0
what is the charge of protons, neutrons and electrons
protons = positive +1
neutrons = natural no charge
electrons = negative -1
what is the radius of an atom
0.1 nm
what is an ion
when the charges of protons and electrons are equal the atom is neutral, yet when the charges are not balanced, the atom is then called an ion (either positive or negative)
what is an element
different types of atoms
what is the number in the bottom left representative of
atomic number and represents the number of protons. this determines the element it is
what is the number in the top right representative of
mass number
what is an isotope
different forms of the same element that have the same number of protons but have a different number of neutrons
what is relative atomic mass
the average mass of all the isotopes that make up an element
what is abundance
how common/rare a specific isotope is
how do you work out the relative atomic mass
sum of (isotope abundance x isotope mass)
————————————————————
sum of abundances of all the isotopes
work out the relative mass of copper
where copper - 63 = 69.2%
and copper - 65 = 30.8%
69.2 x 63 + 30.8 x 65 = 6361.9
69.2 + 30.8 = 100
= 63.6169
what is a molecule
2 or more atoms held together by a chemical bond for example oxygen, water and chlorine
what is a compound
2 or more different elements held together by a chemical bond for example water, carbon dioxide. they are always found in the same proportion for example water = h2o
what is a mixture
containing two or more substances that are not chemically combined together (they haven’t reacted). these are easily separated
who was Democritus
he created the first theory of the atom
- atomic theory
the idea that everything is made up of tiny particles and are separated by empty space
who was John Dalton
- solid spheres
the idea that different shaped/sized atoms where different elements
who created the plum pudding model
J J Thomson
explain the Plum pudding model
the idea that the atoms couldn’t be spheres and Thomson believed atoms were spread out balls of positive charge with discreate electrons in it
who was Earnest Rutherford
he proved the plum pudding model to be wrong
he then created the Nuclear model
- the idea that their was a compact nucleus with a positive charge with negative charge surrounding it
who is Neil Bohr
suggested electrons orbit nucleus and are held in shells
what did Rutherford and James Chadwick discover to add to Neil Bohr’s findings
Rutherford - found protons in nucleus
Chadwick - found neutrons in nucleus
how is an atom stable
needs a full outer shell
how does an atom become stable
the atom needs to react with another atom to gain or loose the electron they need
which shell has the lowest energy level
closest to the nucleus
which group on the periodic table have all their atoms with a full outer shell
the noble gasses - group 0
how do you draw an electron structure for an atom use argon as an example. this has an atomic number of 18
first shell - 2 electrons
second shell - 8 electrons
third shell - 8 electrons
how does the atom calcium become an ion
atomic number of 20
first shell - 2
second shell - 8
third shell - 8
fourth shell - 2
the atom looses two electrons in order to have a full outer shell
this atom is then written in brackets with the two lost electrons. outside the bracket write 2+
if the atom is gaining an electron in order to become stable how is the brackets written out
in brackets yet outside write -x
when x is how many electrons are gained
how are elements arranged
increasing atomic number moving from left to right
explain what information is stated in each box in the periodic table
elemental sign, atomic number (electrons), mass number (protons and neutrons)
what is a period
a specific group of elements that share similar chemical properties
explain what elements in the same group have in common
- the same number of electrons in their outermost shell. The group number tells you how many electrons are in the outer most shell
what did Dobereiner find out
he realised that elements with similar properties often occurred in threes
what law did Newland create
law of octave
- arranged the elements in order of atomic weight, he also stated that every 8th element reacts in a similar way
- because of this, elements were grouped together even if they have different properties
who created the modern periodic table
Dmitri Mendeleev
explain how Dmitri Mendeleev created the modern day periodic table
- started by arranging all the elements in order of increasing atomic weight
- left gaps for future discovery of elements.
what are some differences between the modern day periodic table and Mendeleev’s periodic table
modern day - in order of atomic number (protons)
Mendeleev - protons weren’t discovered and therefore elements were in order of atomic weight. this caused some elements to appear wrong due to isotopes
modern day - has noble gasses
Mendeleev - not been discovered when he created it
how did Mendeleev predict the properties of elements that hadn’t been discovered
he based his ideas on other elements in the same group.
what type of ions do metal and non metal form when they react
metals - positive ions
non metals - negative ions OR don’t form ions
why are metals more reactive as you move down a group
because the outermost shell is further from the nucleus, the positive nucleus can’t hold onto electrons in these shells. therefore they are able to get lost more easily.
what are the physical properties of metals
- metallic bonding
- malleable
- conductors of heat and electricity
- high melting and boiling point
what are the physical properties of non metals
- brittle
- low boiling point
- poor conductors
- lower density
what are the properties of transition metals
- form more than one ion
- good catalysts
what are the group one metals called
alkali metals
what are the properties of alkali metals
the opposite of “normal metal”
- soft, low density, low melting point
- a lot more reactive
as you go down the alkali metals group, what are the properties
- more reactive (calcium ignite at room temperature)
- melting and boiling point decreases
what do alkali metals need to do to be stable and why are does the reactivity increase as you go down the group
loose one electron. as you go down the group, the outer shells gets further away from the nucleus as there is an increased weakness in attractive forces
what happens when an alkaline metal reacts with water
alkali metals + h20 reacts vigorously to form metal hydroxide + hydrogen gas
reactions will release more energy as move down the group, elements near the end of the table could react with the hydrogen gas formed
what happens when an alkaline metal reacts with chlorine gas
when metal is heated in chlorine gas it forms a white metal chloride salt. again reacting more vigorously when moving down the group
what happens when an alkali metal reacts with oxygen
forms a metal oxide
what happens when oxygen reacts with lithium
lithium oxide is formed
what happens when oxygen reacts with soduim
sodium oxide OR sodium peroxide is formed
what happens when oxygen reacts with potassium
potassium peroxide OR potassium superoxide
what is group seven called
halogens
explain what the properties of each element is
- Florine
- chlorine
- bromine
- iodine
fluorine - poisonous yellow gas, very reactive
chlorine - less reactive, poisonous green gas
bromine - red/brown poisonous liquid
iodine - dark grey solid which can form poisonous purple vapour (can be used as an antiseptic)
what is a diatomic molecules
2 atom molecules - covalent bonds
as you go down the halogen group what are the trends
- melting and boiling point increases
- reactivity decreases
why does the reactivity decrease as you go down the group
the outer shell gets further away from the nucleus. attractive forces, which are needed to pull extra electrons for the atom, gets weaker. if a halogen can’t attract an electron to complete outer shell then it can’t react
explain the ionic bonding halogens experience with metals
when reacting with metals ( most likely alkali metals) it becomes a negative ion - becoming a halide
( fluoride, chloride, bromide, iodide)
what is the displacement theory
involves a more reactive halogen displacing a less reactive one
explain the properties of group zero
noble gasses
- all exist as colourless gasses
- all have full outer shells and therefore don’t react with anything
- non flammable
- boiling point increases as you go down the group
