the periodic table Flashcards
how were elements arranged in the early 1800s?
by atomic weight. mass
what were the original 2 ways to categorise elements?
their physical and chemical properties.
their atomic weight.
scientists could only measure atomic weight and had no idea of protons electrons or neutrons
how many elements are there?
~100.
how are elements arranged in the periodic table?
in order of increasing atomic numbers. protons
what do group numbers show?
how many electrons there are in the outer shell.
how does reactivity change when going down group 1?
reactivity increases.
how does reactivity change when going down group 7?
reactivity decreases.
what are periods?
rows across the periodic table. each row represents another full shell of electrons
where are metals on the periodic table and what ions do they form when they react?
metals are bottom left and form positive ions.
where are non metals on the periodic table and what ions do they form when they react?
non metals are top right and form negative ions.
how does the electronic structure of an atom affect how it reacts?
metals to the left of the periodic table have few electrons to lose and metals at the bottom have electrons far away from the nucleus so not much energy is needed to lose electrons.
non metals to the right have lots of electrons to gain and to the top have strong attractions so it is more likely for them to share or gain electrons.
why do atoms react?
atoms react to form a full outer shell by losing gaining or sharing electrons.
what are the properties of metals?
they’re strong.
they’re great conductors of heat and electricity.
they have high boiling and melting points.
what are the properties of non metals ?
dull
brittle.
aren’t always solids.
don’t generally conduct electricity.
what are transition metals?
metals in the centre of the periodic table .
what are the properties of transition metals?
most have multiple ions.
dense, strong and shiny.
often coloured.
often good catalysts. speed up reactions
what are the group 1 elements and what are they known as?
they are alkali metals.
lithium.
sodium.
potassium.
rubidium.
caesium.
francium.
what are the properties of group 1 elements? alkali metals
soft.
low density.
all have 1 electron in the outer shell. very reactive
what happens as you go down group 1?
increases reactivity.
lower melting and boiling points.
higher relative atomic mass.
what happens when group 1 elements react with water?
they react strongly to produce hydrogen gas and metal hydroxides. compounds that dissolve in water to produce alkaline solutions
going down group 1 produces more vigorous reactions and more energy is given off
what happens when group 1 elements react with chlorine?
they react strongly when heated in chlorine gas to form metal chloride salts.
going down group 1 produces more vigorous reactions
what happens when group 1 elements react with oxygen?
they form a metal oxide.
what do alkali metals form with non metals?
ionic compounds.
what are halogens?
non metals in group 7 with coloured vapours. all have 7 electrons in the outer shell
fluorine. very reactive poisonous yellow gas
chlorine. fairly reactive poisonous dense green gas
bromine. dense poisonous volatile red liquid
iodine. dark grey solid or purple vapour
how do properties change as you go down group 7?
less reactive. outer shell is further from the nucleus
higher melting and boiling point.
higher relative atomic mass.
what bond do halogens form with metals?
ionic bonds.
what bonds do halogens form with non metals?
covalent bonds.
when can a displacement reaction occur with halogens?
a more reactive halogen can displace the salt of a less reactive one.
what are the group 0 elements known as?
noble gases.
what are the properties of group 0 elements?
all have 8 electrons in the outer shell. apart from helium
monatomic gases. not bonded to eachother
colourless at room temperature.
non flammable and inert.
