Atomis Structure and the Periodic Table Flashcards
(23 cards)
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…
Example
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.
