Please enable JavaScript.
Coggle requires JavaScript to display documents.
Module 2 Chapter 2 (2.1 Atomic Structure and isotopes (Atomic number…
Module 2
Chapter 2
2.1 Atomic Structure and isotopes
Sub-atomic particles
Protons
Charge-
+1
Mass-
1
Neutrons
Charge-
0
Mass-
1
Hold nucleus together
Electrons
Charge-
-1
Mass-
1/1836
Most of mass in nucleus- where protons and neutrons found
Overall mass of atom= 0
Electrically neutral
p+=e-
Atomic number
Number of protons in an atom
Identifies the element
Every atom of the same element has same number of protons
Periodic table in order of atomic number
Isotopes
Atoms of same element with different number of neutrons but same number of protons and electrons
Chemical reactions involve outer electrons- isotopes react in same way
Have slightly different physical properties
Mass number
Number of protons and neutrons in an atom
Ions
Charged atom
Anions
Negative ions
Gained electrons
Cations
Positive ions
Lose electrons
2.2 Relative Mass
Relative masses used to compare as real masses are too small
Carbon-12
All atomic masses compared to it
Mass exactly known-
-1.99x10-26 kg
Mass of one atom-
12u
(atomic mass units)
Relative atomic mass
Weighted mean mass of an atom relative to 1/12th of the mass of an atom of Carbon-12
Takes into account
% abundance of each isotope
Relative isotopic mass of each isotope
Relative Isotopic Mass
Mass of an atom of an isotope relative to 1/12th of the mass of one atom of Carbon-12
Mass spectroscope
Identifies the relative isotopic mass and relative abundance of each element
How it works
1)
Sample placed in it
2)
Sample vaporised and ionised- +ve ions
3)
Ions accelerated- heavier ions slower- longer to reach detector
4)
Ions detected and appear on mass spectrum
x-axis= m/z
and
y-axis=% abundance
RAM Calculation-
(M1x%)+(M2x%)/100
2.3 Formulae
Ions
Metals lose electrons to form
cations
Non-metals gain electrons to form
anions
Metal Ions
Copper (II)- Cu2+
Copper (I)- Cu+
Iron (II)- Fe2+
Iron (III)- Fe3+
Silver- Ag+
Zinc- Zn2+
Polyatomic ions
1+
Ammonium- NH4+
1-
Nitrate- NO3-
Hydroxide- OH-
2-
Sulphate- SO42-
Carbonate- CO32-
Ion Endings
Ends in
ide
- only that element
Ends in
ate
- something else as well as the element usually oxygen
Covalent
Can deduce most by looking at their name
Mono
- single atom
di
- two
tri
- three
tetra
- four
Ionic
1)
work out formula and charges of separate ions
2)
Work our number of each ion to make it electrically neutral
3)
Put brackets around polyatomic ions present more than once
2.3 Balanced Equations
Reactants
on
left
Products
on
right
State symbols
(S)
- Solid
(l)
- Liquid
(g)
- Gas
(aq)
- Aqueous solution
Atoms cannot be created or destroyed
Key Tips
Put balancing numbers in front of formulae
Don't change any formulae
Add state symbols
You can use fractions
Combustion equation
Only
one mole
of the compound is combusted so fractions may be needed to balance it