3.1 Flashcards
Problems with Antoine Laurent de Lavoisier
Included light and heat, thought to be material
Jons Jakob Berzelius
Table of atomic weights
Letter based symbols
Johan Wolfgang debereiner
Noticed groups of 3 elements ordered by atomic weight, middle had weight and properties, average of other 2
John Newlands
Table, arranged in order of relative atomic weight
Element have similar properties those 8 places in front law of octaves
Mendeleev
Modern based on
Elements ordered by atomic weights
Periodically
Columns, similar properties, groups
Gaps left where none fitted, predicted properties of undiscovered elements
Gallium, germanium, scandium matched these predictions
Order reversed when properties didn’t fit
Henry Moseley
Determined atomic number for all known elements
Properties vary periodically with atomic number rather than weight.
Fixed elements Mendeleev had switched around
Glenn Seaborg
Discovered transuranic elements from plutonium 94 to nobelium 102.
Placed actinide series below lanthanides series at bottom of table.
List makers of period table
Antoine Laurent de Lavoisier Jons Jakob Berzelius Johann Wolfgang dobereiner John Newlands Mendeleev Henry Moseley Glenn Seaborg
What is the table ordered by?
Increasing atomic number starts with hydrogen
Describe periodicity
Horizontal row
Gradual changes in properties across a period in the table
Repeated across each period
Repeated pattern= periodicity
Repeating properties across periods
Predict properties metals to non metals across
Describe groups of the table
Vertical columns
Elements with similar properties
Describe semi metals, metalloids
Non-metals
in between metals and non metals boron etc
Properties between those of metals and non metals
Describe atomic radius
Atomic radii increase too to bottom of group number of shells increases down group and nuclear charge
This decreases the size of individual shells
Describe electronegativity
Increases across period
Decreases down group
Nuclear charge increases electronegativity increases,
Distance from nucleus increases low electronegativity electronpositive
Equation for 1st ionisation energy
X —-> x+ + e-
Equation of second ionisation energy
X+ ——-> x2+ + e-
Equation for third ionisation energy
X2+ ——> x3+ + e-
What state is always used for ionisation energies?
Gas
Define enthalpy
Energy change per mole
Define ionisation energy
Energy to remove electron from an atom
Define first ionisation energy
The amount of energy required to remove one electron from each atom in a mole of atoms; elements in gaseous state
Describe the trend in first ionisation energy
Easier from top to bottom of group
More shells less attraction between outer electron and positive nucleus
Harder across more protons higher force of attraction
With successive ionisation energies when will big differences in energy occur?
Between electron shells because the shell closer to the nucleus will have a greater attraction for the electrons and less shielding from complete shells.
3 factors ionisation energy trends can be explained by
Distance from the nucleus
The nuclear charge/ attraction
The amount of shielding
What did Antoine-Laurent de Lavoisier do?
Produced first modern chemical textbook
Extensive list of elements ‘substances that cannot be broken down further’
Distinguished between metals and non metals
What happens to first ionisation energy down a group and why?
Decreases, electron is further from nucleus, more shielding, even though there is an increase in nuclear charge.
What happens to first ionisation energy across a period?
e.g. Li to Ne
Overall increase in ionisation energy due to the increase in nuclear charge but the same distance from the nucleus.
Drop from Be to B due to shielding from full 2s orbital
Drop from N to O due to electron repulsion when P electrons pair up, easier to remove.
Why do giant metallic lattices have high melting and boiling points?
Electrons are free to move throughout the structure but positive ions remain where they are.
The attraction between positive ions and negative delocalised electrons is very strong.
A high temperature is needed to overcome the metallic bonds and dislodge the ions from their rigid positions in the lattice.
Why are giant metallic lattices good electrical conductors?
The delocalised electrons can mover freely throughout the lattice.
This allows it to conduct even in solid state.
Why are giant metallic lattices both malleable and ductile?
Delocalised electrons, can move the structure has a degree of give which allows atoms or layers to slide past each other.
Define ductile
Can be drawn out of stretched
Permits metals to be drawn into wires.
Define malleable
Can be hammered into different shapes
Many metals can be pressed into different shapes or hammered into thin sheets.