Bonding, Structure, and the Properties of Matter Flashcards
and atomic structure / the periodic table
Describe Rutherford’s particle scattering experiment
- He fired alpha particles at thin gold foil in a vacuum
- Most particles passed through
- Some were deflected as they passed through
- Few were deflected straight back
What did Rutherford’s experiment help him discover?
- Most of the atom is empty space
- Dense, positively charged nucleus
- Mass concentrated at the centre
What did Niels Bohr discover?
That electrons orbit the nucleus at specific distances (energy levels)
In what order were the three subatomic particles discovered?
- Electron
- Proton
- Neutron
What did James Chadwick discover?
Neutrons
Explain Mendeleev’s periodic table
- Ordered by atomic weights (didn’t account for isotopes)
- Left gaps for undiscovered elements
Explain the modern periodic table
- Ordered by relative atomic mass
- Gaps filled in
Name the properties of metals
- Good conductors
- Malleable
- Dense
- High melting points
What is ionic bonding between?
Between oppositely charged ions
What is covalent bonding between?
Between two non-metals
What is metallic bonding between?
Between metals / alloys
How are ionic compounds held together?
Strong electrostatic forces
Why does ____ conduct electricity?
Delocalised electrons that are free to move across the structure
Describe the properties of giant covalent structures
- High melting points
- Insoluble
- Hard
- Electrical insulators
Describe the properties of giant ionic lattices
- High melting points
- When (aq) or (l), can conduct electricity as ions are free to move so charge can flow
Describe the bonding of small molecules
- Strong covalent bonds hold atoms in a molecule together
- Weak intermolecular forces hold molecules together
Describe the properties of small molecules
- Low melting points
- Electrical insulators
- Melting points increase dependent on size of molecules
Describe the bonding in polymers
- Atoms covalently bonded
- Molecules are held together by relatively strong intermolecular forces (solid at RTP)
Why are alloys harder than pure metals?
- In pure metals, atoms are arranged in layers, so they can slide over each other easily
- In alloys, atoms of the other element disrupt these layers, stops sliding
Describe the structure and bonding of graphite
- Arranged in layers held together by weak intermolecular forces
- Atoms in layers covalently bonded
- Delocalised electrons (each carbon has 3 bonds and 4 electrons)
What is graphene used for?
Electronics
What are fullerenes used for?
Electronics, material, and medicine
What are nanoparticles?
- Particles 1-100nm in size
- High surface area to volume ratio
What are nanoparticles used for?
Medicine
Electronics
Sun cream
Deodorant
What is a compound?
Two or more chemicals chemically combined in fixed proportions
Describe the Bohr model and how it came about
Electrons orbit the nucleus at specific distances
Came from alpha scattering experiment
Who discovered neutrons?
James Chadwick
What is the radius of an atom?
0.1 nm
How do you convert nm to mm?
1 nm = 0.000001 mm
1 mm = 1,000,000 nm
What is the radius of a nucleus?
1 x 10^-14 m
How much of an atom does the nucleus make up?
1/10000
Do isotopes of an element have the same chemical properties?
Yes, because their electronic structure is the same
How do calculate relative atomic mass (from abundance)
(Mass x Abundance) + (Mass x Abundance) / 2
What happens to electrons in metallic bonding?
Delocalised electrons are shared
What happens to electrons in covalent bonding?
They are shared
What happens to electrons in ionic bonding?
They are given away
Describe three properties of alkali metals
- Soft
- Low density
- 1 electron in outer shell
Alkali + Water –> ??
Salt + Hydrogen
How does boiling point change going down group 0?
Increases
How are ionic lattices held together?
Electrostatic forces
What are some properties of ionic compounds?
High boiling points
Don’t conduct electricity except when in molten or aqueous form
What are nanotubes?
Allotrope of carbon,
What are fullerines?
Hollow shaped molecules
E.g. Buckminsterfullerene
How big are nanoparticles?
1-100 nm
How big are fine particles?
100-2500 nm
How big are coarse particles?
1 x 10^-5 m and above