atomic structure and the periodic table

Question 1

what is an atom

Answer 1

an atom is a smallest part of an element that can exist

Question 2

what is an element

Answer 2

an element is an substance of only one type of atom

Question 3

how are the elements listed and approx how many are there

Answer 3

they are listed in the periodic table, there are approx 100

Question 4

elements can be classified into 2 groups based on there properties

Answer 4

metals and non metals

Question 5

what is a compound

Answer 5

two or more elements chemically combined together

Question 6

what is a mixture

Answer 6

a mixture consists of two or more elements or compounds not chemically combined together.

Question 7

what are the methods through which mixtures can be seperated

Answer 7

.filtration
.crytillation
.simple distillation
.fractional distillation
.chromotography

they do not involve chemical reactions

Question 8

describe and explain simple distillation

Answer 8

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

Question 9

describe/explain crystillation evaporation

Answer 9

1. 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.
2. 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

Question 10

describe and explain fractional distillation

Answer 10

. 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

Question 11

describe and explain filtration

Answer 11

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

Question 12

describe and explain chromotography

Answer 12

.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.

Question 13

what is a separating funnel

Answer 13

an apparutus for separating immiscible liquids
. two immiscible liquids of different densities will form two distinct layers in the separating funnel

Question 14

describe the plum-pudding model

Answer 14

The atom is a ball of positive charge with negative electron embedded in it.

Question 15

describe the Bohr/nuclear model and how it came about

Answer 15

The nucleur model suggests that electrons orbit the nucleus at specific distances - it came about from the alpha scattering experiments

Question 16

what are the smaller positive particles in the nucleus called

Answer 16

Protons

Question 17

what did the work of james chadwick provide evidence for

Answer 17

the existence of nuetrons in the nucleus

Question 18

describe the structure of an atom

Answer 18

the atom has a small central nucleus , (made up of protons and nuetrons) around which there are electrons

Question 19

state the relative masses and relative charges of the proton,nuetron and electron

Answer 19

PLUS 1= proton
nuetron= 0
electron= -1

Question 20

explain why atoms are electrically nuetral

Answer 20

they have the same number of electrons and protons

Question 21

what is the radius of an atom

Answer 21

0.1nm

Question 22

what name is given to the number of protons in the nucleus

Answer 22

Atomic number

Question 23

atoms of the same element have the same number of which particle in the nucleus

Answer 23

protons

Question 24

where is the majority of mass of an atom

Answer 24

The nucelus

Question 25

what is the mass number

Answer 25

the total number of protons and nuetrons

Question 26

how does one calculate the number of nuetrons using mass number and atomic number

Answer 26

mass number - atmomic number

Question 27

what is an isotope - do isotopes of a certain element have the same chemical properties

Answer 27

. Atoms of the same element that have different number of nuetrons . they have the same chemical properties as they have the same electronic structure

Question 28

what is the relative atomic mass

Answer 28

the average mass value which takes the mass and abundance of isotopes of an element into account where the mass of 12c is 12.

Question 29

what are ions

Answer 29

ions are charged particles . they are formed when atoms lose electrons or gain electrons

Question 30

compare the properties of metals and non-metals

Answer 30

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

Question 31

what is formed when a metal reacts with a non-metal

Answer 31

an ionic compound, made of positive and negative electrodes

Question 32

what is formed when a non-metal reacts with a non-metal

Answer 32

a molecular compound containing covalently bonded atoms

Question 33

explain the following .solute .solvent .solution .miscible .immiscible .soluble .insoluble

Answer 33

. 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

Question 34

in the periodic table are elements in the same group similar or different

Answer 34

they have similar chemical properties , as they have the same number of outer shell electrons

Question 35

in terms of energy levels , what are the differences between elements in the same period

Answer 35

they have the same number of energy levels

Question 36

.electrons occupy particular energy levels , with each electron in an atom at a particular energy level. .which available energy level do electrons occupy

Answer 36

the lowest available energy level

Question 37

the elements of group 0 , are most commonly known as

Answer 37

the noble gases

Question 38

what makes the periodic table periodic

Answer 38

similar properties of elements occur at regular intervals

Question 39

in terms of shells , what is the difference between elements in the same period

Answer 39

they have the same number of shells

Question 39

elements in the same group have the same number of electrons in their outer shell , what does this tell us about their chemical properties

Answer 39

they have similar chemical properties

Question 40

what change in shell number is seen as one moves down the group

Answer 40

the number of shells increases

Question 41

early periodic tables were incomplete and elements were placed in innapropriate groups if what was to be allowed

Answer 41

the strict order of atomic weights

Question 42

knowledge of what made it possible to explain why the order based on atomic weights was not always correct

Answer 42

isotopes

Question 43

mendeleev overcame some problems with the table by doing what . he also changed the order of some elements based on what

Answer 43

. leaving gaps .Atomic weights

Question 44

the majority of elements are

Answer 44

metals

Question 45

elements that react to form positive ions are

Answer 45

metals

Question 46

elements that do not form positive ions are

Answer 46

non-metals

Question 47

elements in group 1 are known as

Answer 47

The alkali metals

Question 48

state 3 charachteristics of the alkali metals

Answer 48

. all have 1 electron in their outer shell .have low density .are stored under oil .are soft

Question 49

.how do group 1 elements react with non-metals . why are these reactions similar for the group 1 metals

Answer 49

.they form ionic compounds which are soluble white solids which form colourless solutions .they all have 1 electron in their outer shell

Question 50

how do group 1 elements react with water

Answer 50

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

Question 51

how does the reactivity change moving down group 1

Answer 51

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

Question 52

statw 5 charachteristics of group 7

Answer 52

. 7 electrons in the outer shell .coloured vapours .diatomic molecules .form ionic salts with metals .form moleculor compounds with non-metals

Question 53

state group 7 elements and there states of matter

Answer 53

. flourine- pale yellow gas .chlorine- pale green gas .bromine- dark brown liquid .iodine- grey solid

Question 54

state 3 changes that occur in group 7 as one moves down the group

Answer 54

. high relative molecular mass .higher melting and boiling point .less reactive -less easily gained electrons

Question 55

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.

Question 56

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

Answer 56

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

Question 57

compare group 1 metals and transition metals

Answer 57

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

Question 58

state 3 common charachteristics of transition metals

Answer 58

.ions with different charges .coloured compounds .catalytic properties

Question 59

what is a catalyst

Answer 59

a chemical substance that increases the rate of chemical reaction. it is not used up over the course of the reaction

Question 60

state the colours of flames when lithium,sodium,and potassium burn in oxygen

Answer 60

crimsion red- lithium yellow-orange- sodium lilac- pottasium

Question 61

describe the properties of noble gases

Answer 61

.non-metals .gases .low boiling points .unreactive the boiling point increases down the group, as the atoms get heavier