Chemistry Revision All Flashcards
Define the ‘periodic table’
Classification of the elements based from comparing their physical and chemical properties
What is in atomic mass?
Number of protons and neutrons combined
How do you find out the number of neutrons in an atom?
Atomic mass - atomic number (protons) = neutrons in atom
What is the row in the periodic table called (horizontal) and what can you find out about it?
Periods, number of electron shells in the number of the period
What are the columns called in the periodic table? What can you find out about it?
Groups, it is number of electrons in the outer (valence) shell
Define ‘valent electron/valence shell?
Number of electrons in the outermost shell
Define ‘element’
Pure substances, cant be broken down further by chemical/physical means, made up by only 1 type of atom
Define ‘atom’
Smallest particle of chemical element that exists (buildings blocks of all matter)
Why are atoms in groups 8 and 4 not reactive?
4 - Hard to gain or lose 4 whole electrons, so hard to bond to become stable
8 - Already full, no point in losing/gaining electrons
Define ‘Ions’
If an atom loses/gains electron to become stable, gains/loses electrons so has a charge
Define ‘Anion’
When an atom gains electrons (negative charge) as more electrons compared to protons
Define ‘Cation’
When atom loses electrons (positive charge atom) as more protons than electrons (less electrons than protons)
Define an ‘Isotope’
When single element/same element has a different number of neutrons than it’s original form on periodic table (same number of protons but different number of neutrons)
What is the rule that states electrons in a re shell are ordered (2,8,8,8…)
Octet rule
Describe the subatomic particle ‘electron’
Symbol = e
Charge = -ve
Atomic mass = 0.0055
Describe the subatomic particle ‘proton’
Symbol = p
Charge = +ve
Atomic mass = 1
Describe the subatomic particle ‘neutron’
Symbol = n
Charge = neutral/no charge
Atomic mass = 1
What is a full key for a Bohr diagram
Key
p = proton (+ve) –> nucleas
n = neutron (neutral/no charge) –> nucleas
dot = electron (-ve) –> electron shell
Predict the charge of a ‘group 1’ atom if it were to bond?
1+, as it will lose 1 electron (1 less electron than proton)
Predict the charge of a ‘group 2’ atom if it were to bond?
2+, as it will lose 2 electron (1 less electron than proton)
Predict the charge of a ‘group 3’ atom if it were to bond?
3+, as it will lose 3 electron (3 less electron than proton)
Predict the charge of a ‘group 4’ atom if it were to bond?
It needs to gain or lose 4 electrons to become stable (too much energy needed to bond)
Predict the charge of a ‘group 5’ atom if it were to bond?
3-, as it will gain 3 electron (3 more electron than proton)
Predict the charge of a ‘group 6’ atom if it were to bond?
2-, as it will gain 2 electron (2 more electron than proton)
Predict the charge of a ‘group 7’ atom if it were to bond?
1-, as it will gain 1 electron (1 more electron than proton)
Predict the charge of a ‘group 8’ atom if it were to bond?
Nothing, because it is already stable and has either 2 or 8 electrons in its outermost shell
Define ‘Inert’
Does not react
What is the chemical formula for ‘Methane’?
CH₄
What is the chemical formula for ‘Ammonia’?
NH₃
What is the chemical formula for ‘Ammonium’?
NH₄⁺
Define ‘Compound’
Pure substances chemically bonded together (only separated through chemical means, not physically)
Composed of 2/more different elements joined by chemical bonds
Define ‘Mixtures’
2 or more substances mixed together (physically)
No chemical change takes place
Separated physically
What is special about group 7?
Halogens
What is special about group 8?
Noble gases (stable)
What is special about group 1?
Alkaline Metals
What is special about group 2?
Alkaline Earth Metals
What are examples of mixtures?
Air, sea water, most rocks
What are examples of compounds?
Water
Carbon dioxide
Magnesium oxide
Sodium chloride
How can compounds be separated?
Chemical reactions, chemical means
How can mixtures be separated?
Easily, physically
What is the property of a mixture?
Each substance is easily separated from the mixture
What is the property of a compound?
The properties are different to the elements it contains
What is the composition of a mixture?
You can vary amount of each substance in a mixture
What is the composition of a compound?
It has ‘definite composition’
Cannot vary amount of each element
Define ‘Chemistry’
Study of the composition, structure and properties of matter and the changes it undergoes
Define ‘Alloy’
A metal made by combining two/more metallic elements together, to give it greater strength (not pure)
What is in a chemical equation?
Reactants –> products
What is plasma?
High temperature, ionized phase of matter as found on the sun
What are all physical properties for elements?
Melting points, boiling points, density, colour, hardness, texture
What are all chemical properties for elements?
Flammability, reactivity
What are three categories of elements?
Metals, non-metal, mettaloids
What are properties of metals?
Shiny, conductors of heat/electricity, malleable, ductile
What are properties of non-metals?
Dull, non-conductors, non-malleable, brittle
What are properties of metalloids?
Semiconductors, characterisations of both metals and non-metals
What 2 things are in a solution?
Solvent, Solute
What is a solvent?
Thing that does the dissolving in a solution
What is a solute?
Thing that gets dissolved in the solution
What are solutions?
A mixture that appears to be a single substance E.G: (salt in water, air in oxygen, nitrogen and oxygen)
Define ‘concentrated’?
Means that theres lots of a substance in a solution (intense)
Define ‘dilute’?
Not concentrated, make a liquid weaker by adding water/another solvent to it
Define ‘colloid’?
Mixture in which particles are dispersed throughout, but no heavy enough to settle (milk, jelly, muddy water)
Define ‘suspension’?
Mixture in which particles of solid material arent dissolved, but suspended in the mixture somewhat evenly throughout the liquid/gas, large enough that they settle out and form sediment eventually (snow globe)
Define ‘Radiation’
Emission of energy through rays/waves or subatomic particles
Define ‘Contamination’
Radioactive material spilled someplace you don’t want it in
Define ‘Chemical equation’
Representation of chemical reaction through symbols of elements to indicate amount of substance in reactants and products
Define ‘Chemical reaction’
Process that involves rearrangement of molecular or ionic structure of substance or compound
Define ‘Ionising radiation’
When radiation collides with atoms/molecules and alters their molecular structure by knocking of electrons, leaving behind ions
How is gamma, beta and alpha rays/particles stopped?
Alpha -> skin/piece of paper
Beta -> thin piece of aluminium
Gamma -> Thick piece of lead
How fast are all three particles/radiaiton?
Alpha –> 10% speed of light
Beta –> 90% speed of light
Gamma –> speed of light
What is the mass of all three radiation?
Alpha –> 4 AMU as 2 protons/nucleas
Beta –> 0.055 AMU or really low (1 electron)
Gamma –> No mass as high frequency electromagnetic wave
What is ionising ability of three radiations?
Alpha –> 20 electrons per ‘a’ particle
Beta –> 1 electron per ‘B’ particle
Gamma –> 1 electron per ‘y’ ray
What occurs during alpha decay?
Nucleas ejects alpha particle (2 protons, 2 neutrons)
Loses 4 atomic mass
Loses 2 atomic number
In which atoms do alpah decay occur?
Mass number greater than 100 or heavy nuclei
How dangerous is alpha radiation/radioisotopes emitting alpha radiation?
If gets inside body, fatal
If outside body it can only travel few cm in air, cant penetrate skin so not dangerous, has potential
How ionizing are all radiations?
Alpha - very as large, heavy, slow and large charge so large attraction to alpha particle (2+)
Beta - Medium power as only 1 electron and can only ionize 1 electron, low charge (close to electron)
Gamma - really low as no charge as it is a high frequency electromagnetic wave (needs direct contact)
What occurs in beta decay?
Neutron converted into proton, and loses 1 electron
Increases atomic number by 1 (creating new element)
How dangerous is beta particle?
Likely to cause radiation burns to skin/eyes as small/fast and CAN PENETRATE SKIN more deeply than alpha
When does gamma decay occur?
When proton/neutrons rearrange inside nucleus and don’t emit any particles (instead gamma ray) as lots of energy and emits light (gamma ray)
Define ‘Transmutation’
Process of atom converting to another element, cant happen through chemical reaction as instead through nuclear decay of the 3
Why chemical reactions cant transmutate?
Chemical reactions involve electrons (ions), while nuclear decay changes in nucleas to change to new element
Define ‘Nuclear decay’
Type of nuclear reaction which can cause atoms to change elements
What occurs and what is radioisotope?
Tiny fraction of atoms have unstable nuclei (radioisotopes) and thus undergo nuclear decay at any time and transmutate after decaying to become more stable and radioactive
Define ‘Half life’
Time takes for half of the nuclei to decay (less than second - millions of years)
Define ‘Nuclear radiation’
Any rays/particles emitted/released by nuclei (alpha, beta, gamma)
Harmful to living organsims
Describe ALL features of covalent bonding
Between non-metals (close periodic table) both want gain to become full
Sharing electrons
Both nuclei equal hold over shared electrons
Can create diatomic gases/elements H2, O2 etc
What are all prefixes for covalent naming?
Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca
What are ALL properties of covalent bonding?
No charges and can’t conduct electricity
Often liquids/gases
Low solubility
Geometrical shaped molecules
Describe ALL features of Ionic Bonding?
Between metals and non -metals
Metals lose electrons to become stable and cation
Non-metals gain electrons from metals to become stable and anion
Form electrostatic attraction form 1 positive, 1 negative ion (oppositely charged ions)
What are ALL properties of Ionic Bonding?
Form crystal lattice structures as (cations attracted to anions and stack up to stable structure)
Soluble in water, partials charges in water disperse anions and cations in ionic compound
High melting points as large amount of energy needed to separate attraction
Conduct electricity in water (electrons free to move between ions)
What are polyatomic ions?
Compound with more than 1 atom
Are non-metals covalently bonded
Entire compound has a charge and can bond ionically AS A GROUP
What are all polyatomic ions? OH1- NO3 1- CO3 2- SO4 2- PO4 3-
Hyrdoxide Nitrate Carbonate Sulfate Phosphate
What is ‘Metallic bonding’?
When multiple metal positive ions are attracted in lattice structure delocalise their valence electrons to form ‘sea of electrons’
Electrons move around each atom, acting as glue and keeping lattice structure strong
Good heat/electricity conductors due to moving electrons
What 5 things are evident in a chemical change?
Release of energy as heat Release of energy as light Change in colour Formation of gas Change in odour
What are all 6 types of chemical reactions?
Neutralization Combustion Synthesis/formation Decomposition Single displacement Double displacement
Describe neutralization
When acid (H donor) and base (OH / H acceptor) react together to neutralise their acidity/base to become more neutral and form salt + water
Acid + Base –> Salt + Water
Describe combustion
AB + O2 –> CO2 + Water
Compound reacts with oxygen to form fire (exothermic), with carbon dioxide and water
Describe synthesis
A + B –> AB
2/more reactants join to form compound
Describe decomposition
AB –> A + B
Compounds like ionic/covalent decompose to produce simple 2/more elements/products
Describe single displacement
A + BC –> AC + B
Replace/swap one element with an element in a compound
Describe double displacement
AB + CD –> AD + CB
Second element from both compounds swap/replace
Form 2 new compounds
Describe ‘Exothermic’
Reaction RELEASES ENERGY as reactants have more energy than products, and need to release to make equal
Releases as heat/light (like fire/combustion as both)
Describe ‘Endothermic’
Reaction absorbs heat (from surroundings) –> making them feel colder
Because products have more energy than reactants and need more energy to fulfill reaction
What is incomplete combustion?
When combustion has limited oxygen to do reaction, being incomplete as and creating ‘dirty carbon’ as soot/smoke/charcoal/carbon monoxide (poisonous gas)
What are the 3 acids and 1 base to memorise?
Sulfuric acid –> H₂SO₄
Hydrochloric acid –> HCL
Nitric acid –> HNO₃
Sodium hydroxide –> NaOH
What are the three acid reactions?
Acid + Base –> Salt + Water
Acid + Metal –> Salt + H₂ (Hydrogen gas)
Acid + Carbonate –> Salt + Water + Carbon Dioxide (CO₂)
What is an acid?
Common, dangerous, can cause burns to skin, some are safe to eat/drink
Stomach acids help digest food
Taste sour Affect indicators (blue litmus --> red) (Methyl orange turns red)
Proton donors –> Donate H+ ions
Strong acid has lots of H+ and weak has little
pH 6 or lower
How do you test for hydrogen gas?
Use lit splint, if pops it is H₂
How do you test for Carbon Dioxide (CO₂)?
Use lit split, if fire goes it, it is carbon
When put carbon dioxide into limewater (Ca(OH)₂), creates a precipitate of calcium carbonate (CaCO3)
CO₂ + Ca(OH)₂ –> CaCO3
How do you test for oxygen?
Should relight a glowing splint because oxygen needed for combustion
What is a base?
Taste bitter
Red litmus turns blue
Phenolphthalein turns purple
H+ acceptors
pH 8 or higher
Examples –> NA
What is an indicator?
Substance that changes colour in the presence of a base/acid
Can detect it using an indicator
Blue litmus –> red with acid
Red litmus –> blue with base
What are all types of indicators?
Universal Indicator
Methyl Blue
Phenolphthalein
