paper 1 mock Flashcards by Cheryl Foudji

How the position of an element in the periodic table is
related to the arrangement of electrons in its atoms and
to its atomic number

they are arranged in order of atomic (proton) number

so elements with similar properties are in columns (groups)

electrons in the same group have the same number of electrons in it’s outer shell- this gives them similar chemical properties

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what are group 1 elements called

alkali metals

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what do group 1 elements react and produce (3)

all react with oxygen to create an oxide
all react with chlorine to form white precipitate , metal chloride salts 2NaCl
all react with water to produce hydrogen gas and metal hydroxides

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how does the reactivity change in group 1 elements

reactivity increases- outer electron easily lost

low melting,boiling points

higher relative atomic mass

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three characteristics of alkali metals

all have 1 electron in their outer shell
soft and have a low density
first three are less dense than water Li,Na,K

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• explain how properties of the elements in Group 1 depend on
the outer shell of electrons of the atoms

reactivity increases as atoms get larger

the distance between nucleus and outer electrons increases

attraction from the nucleus decreases

allowing them to more easily lose electrons

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how do Group 1 elements react with water

release hydrogen and form hydroxides

this dissolves too form alkaline solutions

react vigorously with water

fizzing and moving around the surface of water

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how do Group 1 elements react with oxygen

react with oxygen to create oxide

LI-red flame, white solid
Na-orange flame,white solid
K-lilac flame,make solid immediately

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how do Group 1 elements react with chlorine

to form white precipitate
Li-white powder
Na-yellow flame, cloudwhite powder
K-more vigorous than sodium

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how group 1 metals react with non-metals

form ionic compounds
soluble white solids to form colorless solutions
1 electron in outer shell

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what are group 7 elements called

Halogens

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how properties of the elements in Group 7 depend on

the outer shell of electrons of the atoms

-they all have seven electrons in their outer shell

non-metals

exist as molecules with pairs of atoms Cl(2)

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characteristics of Group 7 elements (5)

7 electrons in outer shell
colored vapors
diatomic molecules Cl(2)
form ionic salts with metals
forms molecular compounds with non-metals

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group 7 elements their states of matter and colour

Fluorine= pale yellow gas
chlorine= pale green gas
bromine= dark brown liquid
iodine= grey solid, purple vapour

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trends in group 7 elements as you go down the group

higher relative molecular mass
higher melting and boiling point
less reactive- less easily to gain electrons

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What are redox reactions?

one substance is reduced and the other substance is oxidised

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what do acids and some metals produce

acid + metal-> salt +hydrogen

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redox reaction of hydrochloric acid and magnesium

2HCl + Mg -> MgCl2 + H2

Mg -> Mg 2+ + 2e - , Mg has lost electrons so Mg has been oxidised
2H + + 2e - -> H2 , H has gained electrons, so H has been reduced

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which metals in the reactivity series will react with acid

those above hydrogen

general equation for neutralization reaction

base + acid-> salt + water

general equation between metal carbonate + acid

metal carbonate + acid -> salt+water+ carbon dioxide

equation for metal oxides + acid

metal oxides + acid -> salt+ water

how is a soluble salt formed

react the excess acid with some insoluble chemical (metal oxide)
filter off left overs
crystallise the product

what does acid and alkalis produce in aqueous soloutions

acids produce hydrogen ions

alkalis produce hydroxide ions

half equations in the extraction of aluminium

bauxite Al203 with cryolite Al 3+ + 3e- --> Al (cathode) 2O2- --> O2 + 4e- (anode) oxygen reacts with C of the anode producing CO2

why is cryolite used in manufacturing of aluminium

lowers the melting point of aluminium oxide, reducing energy costs

uses of nano particles

- medicine - electronics - deodorants - suncreams, better coverage

what is nano science

science that studies particles that are 1-100 nm in size

why do nano particles have better properties than normal size particles

have a higher surface area to volume ratio

find the surface area to volume ratio for a cube with a side length of 10 nm

each face is 10*10=100nm(2) 6 faces so 6*100= 600nm(2) volume of 10cubed= 1000nm(3) 600/1000= 0.6nm(-1)

what do atoms contain

protins neutrons electrons

Describe the plum pudding model

A ball of positive charge with negative electrons embedded in it

describe the Bohr/nuclear model and how it came about

- suggests electrons orbit the nucleus at a specific distance(shells) - came from the alpha scattering experiment

why the new evidence from the scattering experiment led to a change in the atomic model

- the positively charged alpha particles were being repelled and deflected - by a tiny concentration of positive charge in the center of the atom (the nucleus).

Difference between the plum pudding model and nuclear model of an atom

-in the nuclear model negative electrons are not embedded in it rather orbit the nucleus

properties of covalent substances

low melting and boiling points (hydrogen and water)

what are covalent bonds

when non-metal atoms bond together attracted by electrostatic forces, bonds very strong

properties of simple covalent substances

-atoms in molecules held together by strong covalent bonds forces of attraction between molecules very weak as molecules get bigger the intermolecular forces increases so more energy needed to break bonds causing melting,boiling points to increase

what is an exothermic reaction? give examples

energy is transferred to surroundings so surroundings temperature increases hand warmers,selfheating can combustion,oxidation, neutralization negative sign of energy change

what is an endothermic reaction? give examples

energy taken in from surroundings so surroundings temperature decreases thermal decomposition sports injury packs

what occurs in a chemical reaction in terms of bond energies? exo/endo, bond breaking/forming

exothermic - energy released from forming bonds is greater than that needed to break bonds endothermic + energy needed to break existing bonds is greater than the energy released from forming new bonds

what are the advantages (3) and disadvantages (5) of a hydrogen fuel cell

+ no pollutants no recharging only produces water when burnt ``` - flammable hydrogen difficult to store fossil fuel production toxic chemicals expensive production of hydrogen by electrolysis ```

what are the advantages (2) and disadvantages of rechargeable cells and batteries (2)

+ can be recharged by reversing reaction so fuel doesn't need to keep being supplied - hard to dispose of non-biodegradable will eventually stop working, need replace

what is the overall reaction in a hydrogen fuel cell, what are the half equation?

hydrogen goes to anode, oxygen goes to cathode At the cathode (negative electrode) 2H2 –> 4e(-)+4H(+)

what is the overall reaction in a hydrogen fuel cell, At the anode, half equation?

oxygen goes to cathode At the anode (positive electrode) 4H(+) + O2 + 4e(–)→ 2H2O(g)

what is the overall reaction in a hydrogen fuel cell,

overall= | 2H2 + O2 -> 2H2O