Atomis Structure and the Periodic Table Flashcards Preview

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Flashcards in Atomis Structure and the Periodic Table Deck (23):

What does the group number tell you?

how many electrons are in the outer shell


What happens if the outer shell is not full

the atom would react to fill it


1869, problems Mendeelev overcame

he took 50 known elements and arranged them into his table of elements


why did he leave gaps

because the properties of known elements predicted other, as-yet-undiscovered, elements in these locations. This allowed Mendeelev to predict what the properties of the future elements would be.


order in which he arranged the periodic table

mostly in atomic mass, but switched that order if it meant the properties meant it should be changed


properties of metal

good conductor of electricity
high boiling/melting points
strong, but can be bent


atoms normally

gain/share/lose electrons
Metals lose (1+)
Non-metals gain or lose (1-)


the further away from the electron means

a weaker attraction


In 1800, the only thing Scientists could measure

was the atomic mass because they had not yet discovered proton/electrons to order them in atomic number


why was the order of the periodic table wrong in 1800

they placed the elements the wrong way because they were placed in the order of atomic mass


Properties of group 1: alkali metals

very reactive - due to the 1 electron in the outer shell
soft and low density


group 1 metals must be stored under oil

to keep air and water from reacting with them


Group 1 trend

more reactive as it goes down
Higher relative atomic mass
low melting/boiling points


Why does group 1 increase in reactivity?

the atoms get larger
the outer electron gets further from the nucleus
the attraction between the nucleus and outer electron gets weaker - so the electron is more easily lost


Group 0 properties: Noble gases

colourless gases at room temperature
Monatomic gases-not bonded together
Increase in boiling as you go down


Noble gases don't need to lose

or gain any electrons because they have full outer electrons
They dont react with much at all


Boiling point of Radon is -62C and krypton -153C. Boiling point of xenon?

(-153) + (-62) = -215
-215 / 2 = -107.5 = 108


Colours of Halogens

Flurine = RED (g)
Chlorine = GREEN (g)
Bromine = RED-BROWN (l)
Iodine = PURPLE VAPOUR (s)
States are all at room temp (25C)
Colours get darker as you go down


Halogens reactive similarly because

they all have 7 electrons on the outer shell


Halogen trend

higher melting points
higher relative atomic mass
Less reactive - harder to gain an extra electron because the outer shell is further from the nucleus


More reactive halogens will...

displace all of the other halogens from solutions of their salts, and is displaced by none of the others
*Cl2 + 2KI --> I2 + *2KCl


How to find out relative atomic mass:
Cl35 and Cl37 with % of 75% and 25%

(75/100) + 35 = 26.25

(25/100) + 37 = 9.25

26.25 + 9.25 = 35.5


Define an isotope

Isotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers.