Atomic Structure/ Periodic Table

Question 1

name the 4 physical processes used to seperate mixtures

Answer 1

filtration, crystallisation, distillation, chromotography

Question 2

what is filtration?

Answer 2

the process of seperating an insoluble solid from a liquid using filter paper

Question 3

what is crystallisation?

Answer 3

the process of producing crystals from a solution by evaporating the solvent

Question 4

what is distillation?

Answer 4

a seperation technique used to seperate liquid (solvent) from a mixture and keep the liquid part

Question 5

what is chromotography?

Answer 5

a seperation technique used to seperate mixtures of soluble substances (e.g. inks, dyes)

Question 6

name the 5 scientists in order who made discoveries about the atomic model and when they made these discoveries

Answer 6

1. dalton 1803
2. thomson 1897
3. rutherford 1909
4. bohr 1913
5. chadwick 1932

Question 7

what did dalton discover about the atomic model?

Answer 7

1803- all matter is made of small particles called atoms and they are tiny spheres that can not be divided

Question 8

what did thomson discover about the atomic model?

Answer 8

1897- discovered electrons and that the atom can be broken down, his plum pudding model was a ball of positive charge with negative electrons in it

Question 9

what did rutherford discover about the atomic model?

Answer 9

1909- scattering experiment: positively charged alpha particles fired at gold foil bounced back meaning that the mass of the atom was concentrated in the nucleus and that the nucleus is positively charged, lead to nuclear model (atom with ball of positive charge in center and electrons floating around it)

Question 10

what did bohr discover about the atomic model?

Answer 10

1913- electrons orbit the nucleus in shells and the nucleus contains protons

Question 11

what did chadwick discover about the atomic model?

Answer 11

1932- discovered neutrons- he bombarded beryllium atoms with alpha particles and an unknown radiation was produced and he interpreted this radiation as being composed of particles with a neutral electrical charge and the approximate mass of a proton

Question 12

state the relative masses of protons, neutrons and electrons

Answer 12

• protons- 1
• neutrons-1
• electrons- <1 (very small)

Question 13

what is the difference between atomic mass and atomic number?

Answer 13

atomic mass is a larger number, usually above the chemical symbol and the atomic (proton) number is smaller and below the chemical symbol

Question 14

how do you work out the number of neutrons in an element?

Answer 14

atomic mass - atomic number (protons or electrons)

Question 15

why does relative atomic mass take into account the abundance of isotopes of the element?

Answer 15

because if there is much more of one isotope then that will influence the average mass much more than the less abundant isotope will

Question 16

what is relative atomic mass?

Answer 16

the number of times heavier an atom is than one-twelfth of a carbon-12 atom

Question 17

how to work out relative atomic mass

Answer 17

(isotopic mass x abundance) + (isotopic mass x abundance) / 100

Question 18

how are the elements in the periodic table arranged?

Answer 18

• in order of increasing atomic atomic number
• in horizontal rows- periods
• in vertical columns- groups

Question 19

why do elements in the same group have similar chemical properties?

Answer 19

because they have the same number of outer electrons and the same valency

Question 20

how would you use the periodic table to predict the reactivity of an element?

Answer 20

• reactivity increases as you go from left to right across a period
• reactivity decreases as you go down the group

Question 21

describe the early attempts to classify elements

Answer 21

scientists tried arranging elements in order of atomic mass but this left the table incomplete since some elements were unknown

Question 22

explain the creation and attributes of mendeleev’s periodic table

Answer 22

• mendeleev arranged elements in order of increasing atomic weight but also taking into account their properties
• elements with similar properties were put in groups
• the table still had gaps but these successfully predicted the future elements that hadn’t been discovered yet that filled the gaps

Question 23

where are metals and non-metals on the periodic table?

Answer 23

metals are on the left and middle and the non-metals start at a step like shape starting underneath boron

Question 24

compare the properties of metals an non-metals

Answer 24

• metals- high melting/ boiling points, non-metals- low melting/ boiling points (liquid at room temperature)
• metals- good conductors, non-metals- poor conductors
• metals- hard, strong, malleable, shiny, non-metals- weak and brittle

Question 25

describe the noble gases and their lack of reactivity, boiling points and predict trends

Answer 25

• group 0- full outer shells- no tendency to lose, gain or share electrons
• low boiling points
• going down the group- atoms get larger- intermolecular forces between atoms get stronger- more energy is needed to overcome these forces

Question 26

describe the reactivity and properties of alkali metals with reference to electron arrangement

Answer 26

• group 1- very empty outer shell- highly reactive
• low melting/boiling points
• low density
• soft
• reactivity increases down group

Question 27

predict (3) reactions of alkali metals

Answer 27

• alkali metal + water = metal hydroxide + hydrogen
• alkali metal + oxygen = metal oxide
• alkali metal + chlorine = metal chloride

Question 28

describe properties of halogens and how their properties relate to their electron arrangement, inc trends in melting/ boiling points and reactivity

Answer 28

• each molecule is made up of a pair of halogen atoms (single covalent bond) (diatomic)
• group 7- reactive because it only needs 1 electron for a full outer shell
• melting/ boiling points increase down the group because molecules get larger= intermolecular forces get stronger= more energy is needed to overcome forces

Question 29

describe the reactions (2) of halogens

Answer 29

• metal + halogen = metal halide
• hydrogen (non-metal) = hydrogen halide (compound)