the periodic table Flashcards
what does the group number tell you (columns)
how many electrons are on the outer shell
what does the periodic number tell you (rows)
how many shells there are in the electron configuration
how is the periodic table arranged today
in order of increasing atomic number
what does the atomic number tell you
how many protons are in the element/atom. also the amount of electrons, as their values are equal
what does the atomic mass tell you
the amount of protons and neutrons are in the element/atom
how was the periodic table arranged before mendeleev, and what were the problems
scientists attempted to classify the elements by arranging them in order of their atomic weights. this meant that some elements were placed in groups with elements which were not at all similar to them. ex: potassium and argon were next to each other, however potassium is an alkali metal whereas argon is a noble gas.
what did mendeleev do
mendeleev developed a new periodic table by leaving gaps for elements he thought has not been discovered yet. in some places, he changed the order based on atomic weights so that elements with the same properties were grouped together.
why do atoms react
all atoms want to have a full outer shell
what are the 2 liquids in the periodic table
bromine and mercury
describe the practical in which you measure the mass change during a reaction between calcium carbonate and hydrochloric acid. state the balanced symbol equation and the word equation for the reaction.
1) the conical flask and a known volume of hcl are weighed together and recorded
2) a measured mass of calcium carbonate is added to the hcl in the flask. this mass is recorded seperately.
3) the total mass of the flask, hcl, and calcium carbonate is recorded before any reaction occurs- this is the ‘starting mass’
4) the calcium carbonate reacts with the hcl, producing carbon dioxide, water, and calcium chloride. you would see effervescence due to the release of carbon dioxide into the atmosphere. this is known as the law of the conservation of mass, which states: while the overall mass seems to decrease, it’s important to remember that mass isn’t lost. it’s simply converted into gaseous carbon dioxide, which escapes. you’d also see the calcium carbonate gradually dissolve as it reacts with the hcl. sometimes, it may not fully dissolve. after the reaction, the flask and its contents are weighed again to determine the ‘final mass’
5) the difference between the starting mass and the final mass represents the mass of carbon dioxide gas released during the reaction. the change in mass would be negative, as the carbon dioxide escaped into the atmosphere.
CaCO₃(s) + 2HCl(aq) —–> CaCl2(aq) + H₂O(l) + CO₂(g)
Calcium carbonate + Hydrochloric acid —-> Calcium chloride + Water + Carbon dioxide
what does it mean if the mass increases during a chemical reaction
a gas from the atmosphere has reacted with your reactants
what does it mean if the mass decreases during a chemical reaction
one or more of the products are gases that get released into the atmosphere.
group 0 description
group 0 contains non-metal elements. the elements in group 0 are called noble gases. they are inert (very unreactive) because they already have a full outer shell and therefore don’t need to gain or lose any electrons in order to become an ion.
a chemical property is that they have full outer shells. a physical property is that as you go down the group, the boiling point increases because the atoms get larger, so they have stronger intermolecular forces.
why can the solvent not touch the spot of the mixture in chromatography
the ink would dissolve in the solvent and would not move up the paper
what is the distance travelled by the solvent in chromatography
the distance between the 2 pencil lines
what is the residue in filtration
the insoluble substance caught in the paper
what is the filtrate in filtration
the solvent + any soluble substances
what can you use crystallisation for in terms of filtration
separating the solvent + any soluble substances in the filtrate after the filtration process
how do group 1 (alkali metals) elements become ions
they lose 1 electron to form a positive ion of +1
whats a cation
a positively charged ion
whats an anion
a negatively charged ion
how do group 2 (alkaline earth metals) elements become ions
they lose 2 electrons to form an ion of +2
physical properties of transition metals
-electrical conductors
-hard
-high melting/boiling point
-dense
chemical properties of transition metals
-some react with oxygen in the presence of water to rust, like iron
-form coloured compounds
-can be used as catalysts
-can form ions with different charges
-some are very unreactive (silver and gold)
-react with halogens
-react with water
how do group 3 (transition metals) elements form ions
lose 3 electrons to form +3 ions, only aluminium though
how do group 6 (chalcogens) elements form ions
gain 2 electrons to form -2 ions
how do group 7 (halogens) elements form ions
gain 1 electron to form -1 ions
what is argon’s boiling point
220 degrees celsius
what happens as you go down a group in the periodic table
they gain the amount of electrons
what are intermolecular forces
the forces that hold the molecules together. they affect the melting and boiling points of elements.
describe alkali metals (group 1)
-quite soft, can be cut with a knife
-low melting points for metals
-as you go down the group, the reactivity increases
-malleable
-high thermal + electrical conductivity
-as you go down the group it gets easier to lose the outer electron as the electron is farther away from the nucleus(because there’s more shells) which has a positive charge and therefore they don’t attract as much.
how do alkali metals react with water
lithium= not very reactive, effervescence, floated, dissolved. hydrogen gas was produced.
sodium= yellow/orange flame
more reactive than lithium, melts into a sphere shape, floated + dissolved, hydrogen gas was produced, effervescence.
potassium= same as sodium, but lilac flame, no sphere, and more reactive.
what is electron shielding
the further down the group you go, the more electrons there are. therefore, they repel each other and make it easier to remove the electrons/harder to gain an electron. The more electrons, the larger the repulsive force.
describe group 7 (the halogens)
-the colour of the elements gets darker as you go down the group
-the melting and boiling point increases as you go down the group, as the intermolecular forces are bigger, so they’re stronger.
-all elements in group 7 are diatomic, which means they consist of 2 atoms. ONLY when they’re in element form, not compound form.
-less reactive as you go down the group, as it’s harder for them to gain an electron to form an ion.
why don’t group 0 elements bond with other atoms
they already have a full outer shell and therefore don’t need to react with another atom to gain or lose an electron to become an ion.
what makes it harder for an atom to gain an electron
electron shielding, as the electrons repel each other.
also, since the atom is further away from the nucleus as it has a lot of shells for its electrons to sit on, then it will be harder for the electron to get attracted to the positively charged nucleus.
displacement (group 7)
a more reactive halogen will displace a less reactive halogen from its compounds.
why do groups 3, 4 and 5 find it harder to gain/lose electrons compared to groups 1, 2, 6, and 7?
it requires energy to either lose or gain electrons. the greater the amount of electrons needed to be gained or lost, the more energy that’s require to do so. therefore, it’s harder for groups which need to gain or lose more electrons to do so. therefore, we don’t usually see these elements as ions.
what is simple distillation
simple distillation is used for separating out a liquid from a solution
what is fractional distillation
fractional distillation is used for separating mixtures of liquids
