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Chemistry - C1 - Atomic Structure and the periodic table, Chemistry - C1 -…
Chemistry - C1 - Atomic Structure and the periodic table
Chemistry - C1 - Atomic Structure and the periodic table
Properties of transition metals (chem)
Comparison with Group 1 elements
Typical properties
A simple model of the atom, symbols, relative atomic mass,
electronic charge and isotopes
Atoms, elements and compounds
Mixtures
The development of the model of the atom
Relative electrical charges of subatomic particles
Size and mass of atoms
Electronic structure
The periodic table
Metals and non-metals
elements that react to form positive ions are metals
elements that don't react to form positive ions are non-metals
majority of elements are metals (found to the left and bottom of periodic table)
non-metals are found towards right and top of periodic table
Group 0
called noble gases, unreactive (inert) and don't easily form molecules as have full stable outer shell, don't need to give up or gain electrons
going down the group, boiling points increase, and relative atomic mass increases
examples: helium, neon, argon
monatomic atoms, single atoms not bonded
all are colourless gases at room temperature
are inert (unreactive) so are non-flammable and won't set fire
increase in boiling is due to increase in number of electrons, so greater intermolecular forces between them needing to be overcome
Development of the periodic table
before discoveries scientists classified elements in order of atomic weight
early periodic tables, incomplete and mixed up in wrong places
Mendeleev left gaps for new discoveries and changed some elements if didn't match properties of group
isotopes explain why atomic weight order was not always correct
Group 1
known as alkali metals, have single electron in outer shell
reactivity of elements increase when going down the group, melting and boiling points decrease, increase in relative atomic mass
examples: lithium, sodium, potassium
soft and have a low density
don't need much energy to lose one outer electron, form 1+ ions
only ever form ionic compounds
most compounds are white solids that dissolve in water to form colourless solutions
With Water
React vigorously to produce hydrogen gas and metal hydroxides (salts that dissolve in water to produce alkaline solutions)
More reactive (lower down group), more violent reaction is
amount of energy given out, increases going down the group (potassium releases enough energy to ignite hydrogen)
2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
Compared to transition metals
less dense, hard and strong than transition metals
have much lower boiling points
much more reactive than transition elements
With chlorine
react vigorously when heated in chlorine gas, form white metal chloride salts
More reactive (lower down group), more vigorous reaction is
2Na(s) + Cl2(g) -> 2NaCl(l)
With oxygen
forms metal oxide
lithium -> lithium oxide (Li2O)
sodium -> sodium oxide (Na2O) or sodium peroxide (Na2O2)
potassium -> potassium oxide (K2O2) or potassium superoxide (KO2)
The periodic table
arranged in order of atomic (proton) number
elements with similar properties are in groups (columns)
elements in the same group have the same number of outer shell electrons, giving them similar chemical properties
Group 7
called halogens, have similar reactions and 7 electrons in outer shell
non-metals, consist of molecules made of atoms
examples: fluorine, chlorine, bromine, iodine
further down in the group has higher boiling point, melting point and higher relative molecular mass, however less reactive as outer shell is further from nucleus
reactivity of elements decreases as goes down the group
more reactive halogen can displace less reactive halogen from aqueous solution of its salt
all have coloured vapours
fluorine, very reactive - poisonous yellow gas
chlorine, fairly reactive - poisonous dense green gas
bromine - dense, poisonous, red-brown volatile liquid
iodine - dark grey, crystalline solid or purple vapour
all exist are molecules, pairs of atoms
can share electrons via covalent bonding with other non-metals to get full outer shell, compounds that form have simple molecular structures
can form ionic bonds with metals, form 1- ions called halides, theyse have ionic structures
displacement reaction can occur between more reactive halogen and less reactive salt
