Module 2.1 Flashcards by Kitty Harland

brief history of the atom:

dalton: can’t be divided, all of given element are the same, arranged in a table of atomic masses
jj thompson: discovered electrons - plum pudding model negative electrons in sea of positive charge overall neutral
rutherford: alpha particles at gold foil - some deflected - positive nucleus
orbited by negative electrons
bohr: electrons orbited in energy shells
rutherford: proton
chadwick: neutron

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what is the z number

atomic number (no of protons)

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what is the a number

the mass number

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how do different isotopes affect chemical reactions

they don’t as they have the same number of electrons, and chemical reactions involve electrons

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what is relative atomic mass

the weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12

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what is relative isotopic mass

the mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12

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what’s the different between relative formula mass and relative molecular mass

molecular - simple molecules
formula - giant structures

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what is m/z

mass to charge ratio

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what is empirical formula

simplest whole number ratio of atoms in a substance

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ammonium ion charge

NH4 1+

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hydroxide ion charge

OH-

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nitrate ion charge

NO3 1-

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carbonate ion charge

CO3 2-

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sulphate ion charge

SO4 2-

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silver ion charge

Ag+

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Zinc ion charge

Zn 2+

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what is a mole

the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope

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what is molar mass

the per mole of a substance g mol^-1

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what’s the ideal gas equation

pV=nRT
p= pressure Pa
V= volume m^3
n= moles mol
R= gas constant J mol^-1 K^-1
T= temperature K

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what is molar gas volume

the volume per mole of a gas dm^3 mol^-1

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what’s the gas volume equation at RTP

n=V/24

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what is 1 atm in Pa

101000

what is 1m^3 in cm and dm

1000dm^3
1000000^3

0°C in K?

273K

concentration equation

n = c x V

what is a standard solution

a solution of known concentration

what makes an acid concentrated

greater than 10 mol dm^-3

why may percentage yield not be 100%

reaction may be at equilibrium and not go to completion side reactions may occur leading to by-products the reactants may not be pure some reactants or products may be left behind on apparatus used separation and purification may result in the loss of some product

percentage yield equation

actual amount (g) ———————————— x 100 theoretical amount (g)

atom economy equation

Mr of desired product ————————————— x 100 sum of Mr of all products

what is an acid

they release H+ ions in solution a proton donor

weak acid vs strong acid

strong: fully or almost fully dissociate and aren’t good at accepting them back weak: partially dissociate and quickly accept them back

common bases?

metal oxides and hydroxides ammonia amines

what is a base

a proton (H+) acceptor they neutralise acids

what are alkalais

release OH- ions when in an aqueous solution

common alkalais

NaOH KOH NH3

what do you call substances than can behave as an acid and a base and give example

amphoteric substances amino acid (carboxyl group COOH donates proton and amino basic group NH2 which accepts a proton)

what’s the neutralisation reaction

H+ + OH- —> H2O

ammonia reaction with water

NH3 + H2O <—> NH4+ + OH-

why is ammonia a weak base

only a small proportion of the dissolved NH3 reacts with water (equilibrium)

what is hydrated

a crystalline compound containing water molecules

what is anhydrous

a substance that contains no water molecules

what is water of crystallisation

water molecules that form an essential part of the crystalline structure of a compound

how do you calculate water of crystallisation with experimental results

weight of hydrated salt, heat until a constant mass, weight of anhydrous, subtract for weight of water, then divide by mr and put into ratio

what is a diprotic acid

acids that have 2H+ that can be replaced and often need double the base to neutralise eg H2SO4

what is an acid salt

when an H+ on a di/triprotic acid is replaced by a metal but an H still remains

how are titre values shown

to 2 dp with the last number being either a 0 or a 5

brief titration

use pipettes add measured volume of a standard solution into conical flask on white tile and add a suitable indicator place the unknown solution into a burette drop into flask until just neutralised (end point) repeat until concordant and take an average

suggest suitable indicator

phenolphthalein colourless in acid pink in base

oxidation numbers priority

F always 1- H 1+ except in metal hydrides 1- O always 2- except in H2O2 transition metals roman numerals simple ions as expected due to periodic table position (electronegativity to determine priority)

what is the oxidation state

the number of electrons that must be added or subtracted to become neutral

what are oxyanions

negative ions that contain an element along with oxygen

what is reduction in terms of oxidation number

it decreases

what is oxidation in terms of oxidation number

increases