C1 The Atom And The Periodic Table Flashcards
John Dalton discovery
Start of 19th centurt
Atoms were first described as solid spheres
JJ Thomson
1897
Plum pudding model - sphere of positive charge with negative electrons in it
Ernest Rutherford
1909
Nuclear model
Alpha scattering experiment
Niels Bohr
Around 1911
Electrons in shells orbiting nucleus
James Chadwick
Around 1940
Discovered that there are neutrons in the nucleus
Describe the experiment Rutgerford Geiger and Marsden conducted
Fired alpha particles at gold foil
Geiger and Marsden’s experiment showed alpha particles rebounded
Led to theory of nuclear atom
Before the discovery of subatomic particles how was the perioidc table arranged
In order of their atomic weight
Why were some elements wrong place in the early model of the periodic table
Some elements in wrong groups as chemical properties ignored
Law of octaves
Every 8th known element was similar
John Newlands peridoic table ordering
By mass
What was Dmitri mendeleev order of the periodic table
1869 “Father of the periodic table”
Also arranged elements by mass and property, but included empty space for irregular jumps in mass
Why did Mendeleev leave gaps for undiscovered elements in his periodic table?
So elements with similar properties could be placed together
What is the periodic table arrangment of atoms order
Atomic number
Group 1
Alkali metals
Rectivity increases going down group
Increased atomi radii
Reaction for lithium + water
Slow reaction
Lithium doesn’t melt
Fizzing can be see and heard as lithium reacts
Lithium + water ———-> Lithium hydroxide + hydrogen
2Li(s) + 2H2O(l) ——–> 2LiOH(aq) + H2(g)
Reaction for sodium + water
Sodium melts to form a ball that moves around on the surface
Fizzes rapidly before ir disappears
Sodium + water ———–> sodium hydroxide + hydrogen
2Na(s) + 2H2O(l) ———–> 2NaOH(aq) + H2(g)
Reaction for
Potassium + Water → Potassium hydroxide + Hydrogen
Reacts violently
Burns with lilac flame
Melts into a shiny ball that rapidly moves around the surface
What does aq stand for in a chemical reaction
Aqeous solution
Implies the substance in dissolved in water as the solvent
Redox reaction
A chemical reaction that takes place between an oxidizing substance and a reducing substance
Why reactivity of halogens decreases going down the group
Going down the group
Outer electron gets further from nucleus
Atoms get larger
Number of shells increase
Nucleus has less attraction for outer electron so increased shell shielding between the nucleus and outer electron
So an electron is gained easily
Why reactivity increases going down group 1
As go down the group
Atoms get bigger
The outer electron gets further
Attraction between nucleus and last electron gets weaker
So electron more easily lost
Why are noble gases unreactive
All have full outer shell
All non-metal monatomic elements
How do transition metals form coloured compounds
Have ions with different charges
Compare transition metals to group 1 metals
Higher melting points (except mercury)
Higher densities
Stronger
Harder
Less reactive with water and oxygen
2 properties of transition metals that make them suitable for making cutting tools
High melting point
Hard
Not very reactive
Why transition metal oxides added to pottery glazes
Colour
Atom
Smallest part of an element to exist
Element
Substance made up of only 1 type of atom
Metallic
Positive ions in a ‘sea’ of delocalised electrons
Ionic
The strong electrostatic attraction between oppositely charged ions
Covalent
A shared pair of electrons
Why are alloys harder than metals
Different sized particles so the layers can not slide across each other as easily
How prescence of copper atoms in the alloy results in the alloy being stronger than pure aluminum
In pure metals particles same size alloy different sizes
Layers slide over each other easily
In alloys harder to slide over
When does ionic conduct electricity
When ions are free to move
In molten or solution
Describe structure and bonding in sodium chloride
Giant lattice structure with strong electrostatic attraction between molecules
Features of giant covalent structure
Very strong bonds
Very high melting point
Conducts electricity
Buckminister fullerene
Fullerene with formula C60 carbon atoms joined together by strong covalent bonds
Bonds in buckminister fullerene
Medium electrical conductivity
Non-bonding electrons and some double C=C covalent bonds
What can fullerenes be used for
Drug delivery systems in the body, in lubricants and as catalysts
Graphene to nanotube
High electrical conductivity due to non-bonding electron in its structure similar to graphite
High tensile strength
Why diamond has very high melting point
Giant covalent lattice
Strong covalent bonds
Lots of heat required to break bonds
Why fullerene has low boiling point
Weak intermolecular forces of attraction
Little energy required to overcome forces
Formula of gallium ion
+3
Ga
Why discovery of gallium helped mendeleev’s periodic table become accepted
Gallium’s properties aligned with Mendeleev’s predictions
Gas produced when group 1 elements react with water
Hydrogen
Type of bonding in sodium
Metallic bonding
Particles in a sample of neon
Ne-20
Why sodium oxide has high melting point
Strong attractive force between these oppositely charged ions, which require a lot of energy to break
Why oxygen described as reduced in reaction sodium and oxygen
Oxygen atoms have gained electrons
3 differences between nuclear and plum pudding model of atom
No empty space plum pudding model
Positive sphere, only nucleus is positive
Neutrons in the nucleus
Changes Bohr made to the nuclear model
Electrons orbit the nucleus in shells
Mendeleev’s reason for reversing order of periodic table
Order of atomic number
