atomic structure and the periodic table Flashcards
what is an atom
an atom is a smallest part of an element that can exist
what is an element
an element is an substance of only one type of atom
how are the elements listed and approx how many are there
they are listed in the periodic table, there are approx 100
elements can be classified into 2 groups based on there properties
metals and non metals
what is a compound
two or more elements chemically combined together
what is a mixture
a mixture consists of two or more elements or compounds not chemically combined together.
what are the methods through which mixtures can be seperated
.filtration
.crytillation
.simple distillation
.fractional distillation
.chromotography
they do not involve chemical reactions
describe and explain simple distillation
is used to seperate liquid from a solution- the liquid boils of and condenses in the condenser.
The thermometer will read the boiling point of the pure liquid.
to evaporation,we get to keep the liquid
describe/explain crystillation evaporation
- Evaporation is a technique for seperation of a solid dissolved in a solvent
.the solution is heated until , all the solvent evaporates,the solid stays in the vessel. - we remove some of the solvent by evaporation to form a saturated solution.
Then we cool down the solution.As we do it , the solid starts to crystallise, as it becomes less soluble at lower temperatures.
the crystals can be collected and seperated from the solvent via filtration
describe and explain fractional distillation
. fractional ditillation is a technique for separation of a mixture of liquids.
it works when liquids have different boiling points
.the fractionating column contains glass beads. It helps to seperate the compounds.
In industry mixtures are repeatedly condensed and vaporised.The column is hot at the bottom and cold at the top.The liquids will condense at different heights of the column
describe and explain filtration
filtration is used to seperate an insoluble solid is suspended in a liquid.
The insoluble solid gets caught in the filter paper,because the particles are to big to fit through the holes in the paper.
The filtrate is the substance that comes through the filter paper
Apparatus-filter paper+funnel
describe and explain chromotography
.chromotogrpahy is used to seperate a mixture of substances dissolved in a substance
In paper chromotoghraphy , we place a piece of paper with a spot containing a mixture in a beaker with some solvent.
The bottom of the paper has to be in contact with the solvent.
The solvent level will slowly,start to rise, thus separating the spot.
what is a separating funnel
an apparutus for separating immiscible liquids
. two immiscible liquids of different densities will form two distinct layers in the separating funnel
describe the plum-pudding model
The atom is a ball of positive charge with negative electron embedded in it.
describe the Bohr/nuclear model and how it came about
The nucleur model suggests that electrons orbit the nucleus at specific distances - it came about from the alpha scattering experiments
what are the smaller positive particles in the nucleus called
Protons
what did the work of james chadwick provide evidence for
the existence of nuetrons in the nucleus
describe the structure of an atom
the atom has a small central nucleus , (made up of protons and nuetrons) around which there are electrons
state the relative masses and relative charges of the proton,nuetron and electron
PLUS 1= proton
nuetron= 0
electron= -1
explain why atoms are electrically nuetral
they have the same number of electrons and protons
what is the radius of an atom
0.1nm
what name is given to the number of protons in the nucleus
Atomic number
atoms of the same element have the same number of which particle in the nucleus
protons
where is the majority of mass of an atom
The nucelus
what is the mass number
the total number of protons and nuetrons
how does one calculate the number of nuetrons using mass number and atomic number
mass number - atmomic number
what is an isotope - do isotopes of a certain element have the same chemical properties
. Atoms of the same element that have different number of nuetrons
. they have the same chemical properties as they have the same electronic structure
what is the relative atomic mass
the average mass value which takes the mass and abundance of isotopes of an element into account
where the mass of 12c is 12.
what are ions
ions are charged particles . they are formed when atoms lose electrons or gain electrons
compare the properties of metals and non-metals
METALS-
.boiling melting point- high
.conductivity- heat and electricity
.appearance- shiny
.mealliability- yes
.density- high
.oxides- basic
NON-METALS-
.boiling/melting point- low
.conductivity- dont conduct heat,electricity
.appearance- Dull
.mealleability- brittle
.density- low
. oxides- Acidic
what is formed when a metal reacts with a non-metal
an ionic compound, made of positive and negative electrodes
what is formed when a non-metal reacts with a non-metal
a molecular compound containing covalently bonded atoms
explain the following
.solute
.solvent
.solution
.miscible
.immiscible
.soluble
.insoluble
. a solute is a substance that is dissolved in a solvent. together they form a solution
.miscible refers to the substances that mix together. water and oil are immiscible. they do not mix
. soluble refers to the substance that can be dissolved in a solvent.
.insoluble susbatnces wont dissolve in a particular solvent
in the periodic table are elements in the same group similar or different
they have similar chemical properties , as they have the same number of outer shell electrons
in terms of energy levels , what are the differences between elements in the same period
they have the same number of energy levels
.electrons occupy particular energy levels , with each electron in an atom at a particular energy level.
.which available energy level do electrons occupy
the lowest available energy level
the elements of group 0 , are most commonly known as
the noble gases
what makes the periodic table periodic
similar properties of elements occur at regular intervals
in terms of shells , what is the difference between elements in the same period
they have the same number of shells
elements in the same group have the same number of electrons in their outer shell , what does this tell us about their chemical properties
they have similar chemical properties
what change in shell number is seen as one moves down the group
the number of shells increases
early periodic tables were incomplete and elements were placed in innapropriate groups if what was to be allowed
the strict order of atomic weights
knowledge of what made it possible to explain why the order based on atomic weights was not always correct
isotopes
mendeleev overcame some problems with the table by doing what
. he also changed the order of some elements based on what
. leaving gaps
.Atomic weights
the majority of elements are
metals
elements that react to form positive ions are
metals
elements that do not form positive ions are
non-metals
elements in group 1 are known as
The alkali metals
state 3 charachteristics of the alkali metals
. all have 1 electron in their outer shell
.have low density
.are stored under oil
.are soft
.how do group 1 elements react with non-metals
. why are these reactions similar for the group 1 metals
.they form ionic compounds which are soluble white solids which form colourless solutions
.they all have 1 electron in their outer shell
how do group 1 elements react with water
they release hydrogen and form hydroxides which dissolve to form alkaline solutions, react vigaroulsy with water fizzing and moving around on the surface of the water
how does the reactivity change moving down group 1
reactivity increases as the atoms get larger and the distance between the nucleus and the outer electrons increases, thus attraction from the nucelus decreases , allowing them to more easily lose electrons
statw 5 charachteristics of group 7
. 7 electrons in the outer shell
.coloured vapours
.diatomic molecules
.form ionic salts with metals
.form moleculor compounds with non-metals
state group 7 elements and there states of matter
. flourine- pale yellow gas
.chlorine- pale green gas
.bromine- dark brown liquid
.iodine- grey solid
state 3 changes that occur in group 7 as one moves down the group
. high relative molecular mass
.higher melting and boiling point
.less reactive -less easily gained electrons
a more reactive halogen displaces a less reactive one from an aqueos solution of its salt
write the equation and state the colour change seen when chlorine reacts with sodium bromide and when chlorine/bromine reacts with sodium iodine.
a more reactive halogen displaces a less reactive one from an aqueos solution of its salt , explain the trend in reactivity of halogens in these reactions
reactivity decreases down the group.
As we go down the group , the atoms get larger so an incoming electron will be less tightly held by the attractive forces from the nucelus.
thats why cl2 displaces Br and I
compare group 1 metals and transition metals
group 1 metals and transmition metals are heat and electricity conductors
. They are shiny when polished and from ionic compounds with non-metals
.transition metals have higher densities and higher melting and boiling points than group 1 metals. They are less reactive and harder than group 1 metals
state 3 common charachteristics of transition metals
.ions with different charges
.coloured compounds
.catalytic properties
what is a catalyst
a chemical substance that increases the rate of chemical reaction.
it is not used up over the course of the reaction
state the colours of flames when lithium,sodium,and potassium burn in oxygen
crimsion red- lithium
yellow-orange- sodium
lilac- pottasium
describe the properties of noble gases
.non-metals
.gases
.low boiling points
.unreactive
the boiling point increases down the group, as the atoms get heavier
