atomic structure

Atomic structure

first 20 elelments, symbals and elelctron arragnement:

  • hydrogen =
  • helium - lithium =
  • berilium =
  • boron =
  • carbon =
  • nitrogen =
  • oxygen =
  • florine = neon =
  • sodium = magnesium =
  • alimium =
  • silicon =
  • phosphorus =
  • sulfur =
  • chlorine

element on the periodic table

mass number/atomic mass number = no of protons + neutrons ( big number)

atomic number (Z) = the number on the periodic table, - also equals the number of protons, (smaller number)

  • mass number - number protons = nuetrons

structure of an atom

electron configuration/arrangement:


  • electrons don't have fixed paths, but we group them in shells/energy levels, to make it easier to describe


  • each shell has a limit to the no. of elelcrons it can hold


    1st shell = max. 2


    2nd shell = max 8


    3rd shell = max 8


  • the outermost shell holds the valence electrons



valence electrons:

  • the more full the valence shell is the more stable (boring/nonreactive)
  • elements on the same group on the periodic table have the same no. of valence electrons
  • in symbols/equations only valence electrons are mentioned as these are important in determining some of the chemical behaviors
  • center of an atom is made of protons and neutrons , & it is positive.
  • the electrons around the nucleus are negative
  • majority of an atom is made up of 'empty' space

difference between an atom and an ion

atoms = the smallest thing to exist on its own

ions ( simple ion formed from an atom) =
ions are atoms/molocules witch have gained or lost one or more valence electron giving the ion a negative or positive chanrge

  • they are charges elements
  • ions form from ionic bonding
  • atoms 'want' to have full valence shells, in order to do this they must gain or lose electrons
  • they will always choose the easiest one
    (e.g. it is easier to gain 1 than lose 7, to make a full outer shell of 8)
  • ions are formed from atoms
    - ions have full valence shells
    ( you can only gain or lose electrons, not protons)

monotomic ions vs. poliatomic ions

polyatomic ions:

  • mono = 1
  • single atoms that has lost / gained electrons (ionic bonding)
  • have subscript numbers
  • examples; Cl- or Cu2+ or Al3+

monatomic ions:

  • poly = many
  • group of atoms that has lost / gained electrons
  • atoms held together by sharing electrons (covalent bonding)
  • have subscript numbers and superscript numbers
  • examples; NO3 - or CO3 2-

Basic ions, their formula & charges:

  • ammonium ion = NH4 +
  • sodium ion = Na +
  • potassium ion = K +
  • silver ion = Ag +
  • hydrogen ion = H +
  • calcium ion = Ca2 +
  • zinc ion = Zn 2+
  • alumium ion = Al 3+
  • iron (II) / ferous ion = Fe 2+
  • iron (III) / ferric ion = Fe 3+
  • magnesium ion = Mg 2+
  • Copper ion = Cu 2+
  • lead ion = Pb 2+

  • barium ion = Ba 2+


  • oxide ion = O 2-

  • sulfide ion = S 2-
  • carbonate ion = CO3 2-
  • solfate ion = SO4 2-
  • hydroxide ion = OH -
  • chloride ion = Cl -
  • nitrate ion = NO3 -
  • hydrogen carbonate / bicarbonate ion = HCO3 -

steps by witch the ions are formed, some examples;


Calcium atom:

  • symbol = Ca
  • atomic number = 20
  • electron arangement = 2,8,8,2
  • electrons arrangement of ion = 2,8,8, (it has lost 2 elelctrons to ave a full valence shell -2)
  • ion symbol/charge = Ca2+

Florine atom:

  • symbol = F
  • atomic number = 9
  • elelctron arrangement = 2,7
  • electron arrangement of ion = 2,8 ( it has gained 1 elelctron, to fill the valence shell +1)
  • ion syble = F-

how to write; formation of ions in relation to electron arrangement and no. of protons and electrons

example: (Calcium)
Calcium atom (Ca) has 20 protons and 20 electrons, with an electron arrangement of 2,8,8,2. the atom must loose 2 electrons in order to have a full valence shell. the calcium ion will now have 2 more protons that electrons, and therefor have a positive charge of 2+. the ion has only 18 electrons and an electron arrangement of 2,8,8. it has a positive charge and is therefore a cation. calcium is in group 2, group 2 elements are generaly quite unstable as it has such an empty valce shell, however clacium ion is now stable.

what to include:

  • group number
  • protons and electron arrangement of atom
  • protons and electron arrangement of ion
  • charge & if its a cation/anion
  • ( Cl- & Ca2+ bothe now have the same electron configuration of 2,8,8

rules for the names of ions

  • ides are all monoatomic &ates are all polyatomic +contian oxygen
  • the name of simple positive ions have the same name as the atoms they are formed forme
  • the name of simple negative ions change the atom name to the end into -ide
  • the name of a negative ion with a polyatomic ion changes the nae of the atom to end in -ate (has oxygen in it)

ways ion charges are written:

  • charge of the ion = superscript (top of the symbol)
    • number of each kind of atom in an ion (polyatomic ions)
      = subscript (bottom of symbol) - ratio of the different elements in the substance

there are two types of ions; cations (+) and anions (-)

anions (-) :

  • anions have a negative charge (-)
  • anions have gained electrons , therefor have more electrons than protons.

the difference between cations(+) and anions(-), is their net electrical charge (they are both ions)

metals vs. non metals

non-metals = generally have a large number of valence electrons ( 5,6,7,8). so atoms require gaining electerons to create ions, this gives them a negative charge (anions -)

metals = generally have small no. of valence electrons (1,2,3). so atoms require losing electrons to create their ions, this gives them a positive charge (cations +)

cations (+):

  • cations have a positive charge (+)
  • cations have lost electrons, this means there are more protons than electrons
  • ( in an atom) no. of Electrons = no. of protons
  • ( in an ion) no. of electrons doesn't equal no. of protons

Ions/Atoms NCEA question template

E = Electrons
B = Bend
C = Charge
R = Ratio


E:

  • Atoms that form compound
  • electrons lost/gained from those atoms to form the ion
  • gains/ looses certain amount of electrons to fill the valence shell - witch is a cation/anion
  • no. of protons & electrons in each ion
  • every ... reacts with .... of ... to make the compound

B:

  • bond forming ... compound is an ionic bond
  • ionic bond, loose, gain, exchange electrons
  • ... number of electrons gained/lost and given/taken from ... to fill outer shell
  • attraction between cation & anion, oppositely charged ions

C:

  • is an ionic substance
  • (for each) (name) ion is (formula), has charge of ... (... more/less electrons than protons)
  • ionic substance/compound can't have overall charge (charge of zero)
  • individual ion charges, that make up compound must cancel each other out

R:

  • for the compoun (name and formula) there is ... number of this ion & ... number of that
  • Al3+, Cl,Cl ( example)
  • tranfers ... electrpns from... ions to ... number of this many ions
  • to make overall charge of zero ( no charge)
  • ration written as (example) Al3+ : Cl- is 1:3, for each compound
  • ration for compound written as subscript, making .... formula

isotopes:

isotopes are atoms that have the same number of protons and electrons, but a different number of neutrons

changing the number of neutrons in an atom doesn't change the element, they are just an isotope of that element, (a type of variation of that element)

  • most elements can have isotopes
    ( but most of them won't have more that 3 different types of isotopes)
  • carbon dating uses isotopes

isotopes are physical the same and chemically act the same

(carbon dating ;

  • uses isotopes
  • when you die you have carbon14 ( an isotope of carbon) in your bones . but as your body ages the carbon14 degrades and you will have more 12 & 13)

Matter

pure substances

elements = 1 type of atom, all have different structure and properties. an element can't be divided into any smaller/multiple elements

non metals = all elements that aren't metals

  • typically gas @ room temp. - brittle
  • low conductivity
  • right hand side of the periodic table

metals = majority of elements

  • typically have a solid state @ room temp.
  • shiny
  • conduct heat and electricity well
  • hard density - malleable
  • left hand side of the periodic table

compounds = two or more elements chemically combined

mixtures = to or more elements combined in a mixture, not chemically combined (easily separated)

chemical vs. physical changes

physical changes:

  • no new substance in formed
  • easily reversed

changes in state are physical changes

chemical changes: