Elements and the periodic table

Question 1

Matter

Answer 1

Anything that occupies space and has a mass

Question 2

Solids

Answer 2

Fixed 3D lattice
Attraction between particles very strong- high MP and BP
Only vibrate- don’t move out of fixed positions

Question 3

Liquids

Answer 3

Particles disordered- collide into each other and walls of the container
volume remains constant
attraction between particles weaker than in solid state

Question 4

Gases

Answer 4

Particles far apart and disordered
Collide into each other and move until they collide with the walls of the container
volume is not constant
Attraction between particles weakest

Question 5

Mass

Answer 5

Measure of the quantity of matter in an object, regardless of the gravity force

Question 6

Weight

Answer 6

Force that gravity exerts on an object

Question 7

Substance

Answer 7

Form of matter with constant composition, distinct properties and can write a chemical formula

Question 8

Mixture

Answer 8

combination of two or more substances
no constant composition
cannot write a chemical formula

Question 9

Element

Answer 9

Substance made of only one type of atom

Question 10

Compound

Answer 10

Substance made of two or more different types of atoms

Question 11

Chemical identity of an atom

Answer 11

Determined solely by its atomic number

Question 12

Isotopes

Answer 12

Atoms that have the same atomic number but different mass numbers
Protons an electrons determine chemical properties of an element
Neutrons dont take part in chemical reactions

Question 13

Isotope similarities

Answer 13

Atomic number
Chemical properties
Number of electrons

Question 14

Isotope differences

Answer 14

Mass number
Number of neutrons
Stability of nucleus

Question 15

MP and BP table

Answer 15

Solid Liquid Gas
MP + - -
BP + + -

Question 16

Hydrogen spectra

Answer 16

Neils Bohr’s shell model
Visible hydrogen spectrum consists of four lines (red, green, blue and violet) observed by passing an electric current through hydrogen gas
electrons move around nucleus at specific energy levels
can transition from a lower energy level to a higher energy level by absorbing energy
higher energy electron- excited state
excited electron is unstable and falls back to ground state, emitting the absorbed energy
This energy corresponds to the coloured lines on the spectrum
electron in lowest possible energy shell- ground state

Question 17

Schrodinger

Answer 17

Quantum mechanical model
electrons form a cloud of negative charge around the nucleus
shells, sub shells, orbitals

Question 18

Valence electrons

Answer 18

involved in chemical reactions because they are unstable

Question 19

Octet rule

Answer 19

Outermost shell can never contain more than 8 electrons regardless of the maximum possible number for that shell

Question 20

Max no. electrons in shell

Answer 20

2

2n

Question 21

Pauli principle

Answer 21

Gives the number of electrons in any orbital

An atomic orbital can hold a maximum of two electrons

Question 22

4s and 3d

Answer 22

Electrons occupy the lowest energy sub-shell in an atom first
As shells move away from the nucleus, they get closer to each other
As they get further away, in some cases, the sub shell of one shell are higher in energy than the sub shell of the next shell
3d sub shell is higher in energy than 4s subshell so 4s must be filled first

Question 23

Ions

Answer 23

Atoms have either gained or lost electrons and are no longer neutral but have an electrical charge

Question 24

Cations

Answer 24

Lost electrons
Positively charged
Metals

Question 25

Anions

Answer 25

Gained electrons Negatively charged Non-metals

Question 26

Dalton

Answer 26

Atomic theory - All matter is composed of tiny, indivisible particles called atoms (SUBATOMIC PARTICLES) - All atoms of the same element are identical in mass and properties (ISOTOPES) - Compounds have atoms of different elements combined in whole number ratios - Atoms are neither destroyed or created in chemical reactions - most stable compounds of two elements contain atoms in a one-to-one ratio (CAN BE ANY RATIO)

Question 27

Lavoisier

Answer 27

Law of conservation of mass | During a chemical reaction, the mass of reactants is equal to the mass of the products

Question 28

Mendeleev

Answer 28

Early periodic table Arranged in order of increasing atomic masses Groups of elements had similar properties Gaps were left for unknown elements, predicted their properties

Question 29

Modern periodic table

Answer 29

Discrepancies were resolved Elements arranged according to increasing atomic number Elements classified according to atomic numbers and electrons configurations Same group, same number of valence electrons Same period, same number of occupied electron shells

Question 30

s-block

Answer 30

2 columns- because s sub shell has one orbital and a maximum of two electrons I alkali metals II alkaline earth metals highest energy electron is in s-sub shell

Question 31

p-block

Answer 31

6 columns- because p sub shell has 3 orbitals and a maximum of 6 electrons VII halogens VIII noble gases highest energy electron is in p-sub shell

Question 32

d-block

Answer 32

10 columns- because d sub shell has 5 orbital and a maximum of 10 electrons transition metals highest energy electron is in d-sub shell

Question 33

f-block

Answer 33

14 columns- because f sub shell has 7 orbital and a maximum of 14 electrons 4f- lanthanides 5f- actinides highest energy electron is in f-sub shell

Question 34

Nuclear charge

Answer 34

equal to atomic number Lithium- nuclear charge is +3 but the full force of this charge is partially offset by the mutual repulsion of the two 1s electrons the 2s electron is shielded from the nucleus by the other electrons

Question 35

Electron shielding

Answer 35

Electrons in a given shell are shielded by electrons in inner shells but not by those in outer shells Inner filled shell electrons shield outer electrons more effectively than electrons in the same sub shell shield each other

Question 36

Core charge

Answer 36

Effective charge of the nucleus that is experienced by the outer shell electrons inner shell electrons shield the protons in the nucleus so the outer shell electrons experience reduced attraction core charge= group number= atomic no.- inner full shell electrons

Question 37

Atomic radius

Answer 37

Distance from nucleus to valence shell

Question 38

Metallic character

Answer 38

Tendency of an atom to lose electrons, and form a cation

Question 39

Ionisation energy

Answer 39

The minimum energy required to remove an electron from a gaseous ground state atom or ion Takes less energy to remove the first electron from the ground state atom and more energy is required for remaining electrons from resulting ion

Question 40

Why does it take less first IE for first electron?

Answer 40

Electron shielding results in a weaker attraction of the nucleus for each electron When first electron is removed, fewer electrons are present so there is less shielding and electrons feel larger effect of the nuclear charge

Question 41

Highest and lowest first IE

Answer 41

``` Highest= noble gases lowest= group one ```

Question 42

Size of cations

Answer 42

Cation is smaller than neutral atom because cation's valence shell is pulled towards nucleus with more effective nuclear charge

Question 43

Size of anion

Answer 43

Anion is bigger than neutral atom because anion valence shell is pulled towards the nucleus with less effective nuclear charge

Question 44

Metal reacitivty

Answer 44

depends on first ionisation energy as metals lose electrons in chemical reactions

Question 45

Non-metal reactivity

Answer 45

Depends on electronegativity as non-metals gain electrons in chemical reactions

Question 46

Chromium

Answer 46

4s1 3d5

Question 47

Copper

Answer 47

4s1 3d10

Question 48

Chromium and copper exceptions

Answer 48

Because the most stable electron configurations are when the sub-shell is half or completely filled with electrons, to minimise electron repulsion, the subshell is half-filled first

Question 49

Electron transfer from 4s to 3d

Answer 49

Possible because energy of 4s and 3d are almost the same Electron transfer increases the stability of the atom Only occurs in the d-block, when d sub shell is almost half or completely full