periodic table Flashcards
what does the group represent?
valency (number of valence electrons)
—same group = same valency = similar chemical properties
what does the period represent?
number of electron shells
—same period = same number of electron shells
across a period elements change from…
metals to non-metals
what are metalloids?
elements that have both the properties of metals & non-metals
(B, Si, As)—along the zig-zag line
what is metallic character?
ease at which the atom of an element forms a positive ion through the loss of electrons
(metals have high metallic character as it is easier for them to LOSE a few electrons rather than gain many)
does metallic character increase/decrease along the period?
decrease.
across a period, proton number increases while number of electron shells remain constant
= increased attraction between nucleus & valence electrons
= decrease in the ability to lose valence electrons
does metallic character increase/decrease down the group?
increase.
number of electron shells increase down the group
= valence electrons are further away from the nucleus
= force of attraction between nucleus & valence electrons decrease/weaker
= ability to lose electrons increase
what are the elements in period 3?
Na, Mg, Al, Si, P, S, Cl, Ar
what are the structures of the elements in period 3?
Na, Mg, Al (metals):
giant metallic lattice structure
Si (metalloid):
giant covalent structure
P, S, Cl, Ar (non-metals):
simple molecular structure
what are the type of bonding in period 3?
Na, Mg, Al (metals):
strong FOA between positive ions & sea of delocalised electrons
Si (metalloid):
strong covalent bonds between atoms
P, S, Cl, Ar (non-metals):
weak IMFOA between molecules (except Argon: weak interatomic forces)
what are the variation in m.p. in period 3?
Na, Mg, Al (metals):
no. of valence electrons increase
= strength of electrostatic FOA increase
= m.p. increase
Si (metalloid):
giant covalent structure
= require large amount of energy to break the strong Si-Si covalent bonds
= m.p. reaches a max
S, Cl, Ar (non-metals):
simple molecular structure
= smaller molecule size
= weaker IMFOA
= little energy required to overcome weak IMFOA
= m.p. drops/is low
what is the electrical conductivity in period 3?
Na, Mg, Al (metals):
no. of valence electrons increase
= no. of delocalised electrons increase
= electrical conductivity increase
Si (metalloid):
all valence electrons are involved in covalent bonding
= electrical conductivity drops sharply
P, S, Cl, Ar (non-metals):
no valence electrons available as they are all involved in covalent bonding
= electrical conductivity drops to zero
what are elements of group 1?
alkali metals:
lithium, sodium, potassium, rubidium, caesium, francium
(most reactive metals)
what are the 6 properties of group 1?
- soft: can be cut easily
- low density (increases down the group, except for potassium)
- low m.p. (decreases down the group)
- similar chemical properties (due to same valency)
- reducing agent
- highly reactive
why does group 1 have low m.p.?
proton number is constant (due to the group) while electron shells increase (due to period)
= weaker electrostatic FOA between positive ions & sea of delocalised electrons
= less energy required to overcome weak electrostatic FOA
= low m.p.
why does group 1 have high reactivity?
weak electrostatic FOA between nucleus & valence electrons
= atoms loses valence electrons more easily
= more reactive
metal + water reaction?
metal + water —> metal hydroxide (alkali) + hydrogen
group 1 metals reaction to water?
lithium: reacts quickly, floats on water, no flame
sodium: reacts very quickly, yellow flame
potassium: reacts violently, lilac flame
rubidium: reacts very violently, no flame
elements in group 17?
fluorine, chlorine, bromine, iodine, astatine
what are 8 properties of group 17?
- most reactive non-metals
- exists as diatomic covalent bonds
- form acids when bonded to hydrogen (e.g. HCl, HF, HBr)
- m.p. & b.p. increases down the group
- do not conduct electricity
- becomes darker down the group
- reactivity decreases down the group
- oxidising agent (itself reduces)
why does the m.p. & b.p. increase down the group?
go down group
= molecular size increases
= IMFOA becomes stronger
= require more energy to overcome
what is the structure of group 17?
simple molecular structure
why can’t group 17 conduct electricity?
since halogens have simple molecular structures, all their molecules are involved in covalent bonding and hence have no mobile charge carriers (e.g. positive ions or electrons)
= neutral molecules
why does the reactivity for group 17 decrease down the group?
atomic size increases (as electron shell number increase down a group)
= valence shell further away from nucleus
= electrostatic FOA between valence electrons & nucleus weaker
= ability to attract an electron decreases
metals gain or lose electrons?
non-metals gain or lose electrons?
metals: lose electrons (it’s easier for them to lose a few rather than gain many)
non-metals: gain electrons
order of group 17 reactivity?
- fluorine
- chlorine
- bromine
- iodine
- astatine
explain displacement in group 17?
more reactive displaces less reactive from halide solution
halide solution: any solution that contains a halogen (normally aqueous)
- it is a redox reaction as electrons are transferred from the less reactive halogen ( in its halide solution) to the more reactive halogen
what are the elements in group 18?
noble gases: helium, neon, argon, krypton, xenon, radon
what are 6 properties of group 18?
- inert, do not undergo reaction readily (easily)
- monoatomic gases
coloured & odourless gases at r.t.p. - very low m.p. & b.p.
- do not conduct electricity
- insoluble in water
why are the elements in group 18 inert?
they have a fully-filled valence electron shell (either duplet or octet structure) & do not need to gain/lose electrons to achieve stable electronic configuration
why doesn’t group 18 conduct electricity?
they have no mobile charge carriers (ions or electrons) to conduct electricity
uses of noble gases?
helium: fill balloons
neon: lights & advertising signs
argon: fill light bulbs
what groups are transition metals?
group 3-11
colour of fluorine (Fl2) at r.t.p. & aq solution?
r.t.p: pale yellow gas
aq solution: nil
colour of chlorine (Cl2) at r.t.p. & aq solution?
r.t.p: yellow-green gas
aq solution: yellow-green solution
colour of bromine (Br2) at r.t.p. & aq solution?
r.t.p: red-brown liquid
aq solution: red-brown solution
colour of iodine (I2) at r.t.p. & aq solution?
r.t.p: purple-black liquid
aq solution: brown solution
halogen vs halide?
halogen: gas form (e.g. Cl2, Br2)
halide (ion): natural form (e.g. Cl-, Br-)
what are 5 properties of transition elements?
- high m.p. & b.p.
- high densities
- variable oxidation states in their compounds
= can form ions with different oxidation states - form coloured compounds
- make good catalysts
what is the definition of catalysts?
a substance that increases the rate of a chemical reaction & remains chemically unchanged at the end of the reaction
