PDP Chemistry
Atomic structure
Topic 2: Atomic structure
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solids, liquids and gases
pressure volume and temperature in a gas
models of the atom
subatomic particles
electron arrangement
converting units
measuring chemical quantities
Phases of matter
How do we classify matter?
Particles in solids, liquids and gases
Think
Pair
Share
Size of an atom
How big is a carbon atom?
stearic acid
monolayer
1% stearic acid solution
Modelling a cylinder V = πr2h
Why are we uncertain about the result?
Percentage uncertainties: How much do
we know what we don’t know?
 percentage uncertainty = uncertainty/value x 100
 for example 20±2cm
 % uncertainty = 2/20 x 100 = 10%
 sig figs!
Quantifiable uncertainties in size of a
carbon atom
Variable
Value
Absolute
uncertainty
% uncertainty
What other factors affect how accurate
your result is?
Factor affecting accuracy
Does it make the final result higher
or lower?
Carbon atom
Covalent radius
sp3: 77 pm
sp2: 73 pm
sp: 69 pm
Van der Waals radius
170 pm
1pm = 10-12m
Image: ttp://salihabava.com/2012/10/we-create-in-play/.
They’re much too small to see
so how do we know atoms
exist? And how do we know
what they’re made of?
H2O
How do we know about atoms?
Atoms

substances combine in fixed ratios

kinetic theory of solids, liquids and gases

scanning tunneling microscopy

Brownian motion
Atomic structure

cathode rays

Geiger-Marsden gold foil experiment

emission spectra

radioactivity

particle accelerators
How do we know about
atoms?
Combination in fixed ratios
 2g of hydrogen and 16g of oxygen make 18g of water
 4g of hydrogen and 32g of oxygen make 36g of water
H2O
Kinetic theory- microscopic model to
explain macroscopic properties
Melting and boiling
Compressibility
Pouring
Brownian motion
Image: https://en.wikipedia.org/wiki/Brownian_motion
Brownian
motion YT
from 4 min
Scanning tunnelling microscope images
Iron atoms on copper, Image:
http://www.almaden.ibm.com/vis/stm/atomo.html
How do we know about
atomic structure?
Cathode rays
Geiger-Marsden gold foil experiment
Radioactivit
y
Emission spectra
https://en.wikipedia.org/wiki/Balmer_series,
https://en.wikipedia.org/wiki/Flame_test
Particle accelerators
Image: https://en.wikipedia.org/wiki/Particle_accelerator
How is an atom structured?
Atomic structure PEN
Charge
Proton
Neutron
Electron
charge = 1.602176565 × 10−19 C
charge = 0
charge = −1.602176565 × 10−19C
Mass
Proton
Neutron
Electron
mass = 1.67262158 × 10-27 kg
mass = 1.674927352 × 10−27 kg
mass = 9.10938291 × 10−31kg
Simpler units
relative charge proton = +1
electron = -1
relative mass proton = 1.007 u
neutron = 1.008 u
electron = 0.000 5485 u
(unified atomic mass unit)
Atomic number (Z) is the number of protons in the nucleus
Mass number (A) is the number of nucleons (protons +
neutrons)
Isotopes are atoms of the same element with different
numbers of neutrons (and a different mass number)
Mass number 
Atomic number 
7
Li
3
Atomic mass (atomic weight)
How are electrons
arranged around an
atom?
Models of the atom
Bohr model
Emission spectra
hf
energy emitted as
photons when electrons
move between energy
levels
Ionization energy
2500
Ionization energies of the first 100 elements
Ionization energy kJmol-1
2000
1500
1000
500
0
1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100
Atomic number
Electrons arranged in shells
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
Periodic table and
electron shells
Standard periodic table
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
Newland’s PT, 1866
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
Mendeleev’s PT, 1869
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
Spiral PT,
modern
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
List the physical and chemical properties
of A,B,C,D and E
www.webelements.com
Write at least 5 sentences about how the
periodic table is arranged.
Image:
https://en.wikipedia.org/wiki/Peri
odic_table
Periodicity
Trends in the periodic table
Image: https://en.wikipedia.org/wiki/Periodic_trends
Important groups
1. Alkali metals
2. Alkali earths
17. Halogens
18. Noble gases