Chemistry Y9 Flashcards
What is an isotope?
Atoms of the same element and same number of protons but different number of neutrons
How many electrons would be in the outer shell of an element in group 7?
7 electrons in the outer shell
What is a molecule?
Two or more atoms of the same or different elements chemically bonded
Why is rubidium more reactive than potassium?
Rubidium is larger so the negative outer shell of electrons is further away from the positive nucleus. Therefore the electrostatic attractions weakens so its easier to lose electrons- therefore it’s more reactive
What did Rutherford conclude in the Alpha Scattering experiment?
Most of the particles went through - mostly empty space
Some were repelled - repelled by something positive
Some rebounded fully - Hit something small, dense and positive (nucleus)
What is the mass of protons, neutrons and electrons
Proton: 1
Neutron: 1
Electron: 0
What are the charges of electrons, protons and neutrons?
Proton: positively charged
Electron: negatively charged
Neutron: no charge
What is solubility?
A measure of how much a substance dissolves
What is a solvent?
A liquid that dissolves a substance
What is a solution?
Formed when a solid dissolves in a liquid
What is a solute?
A substance that dissolves in a liquid
What is retention Factor (Rf)
Measure of solubility
What is the law of the conservation of mass?
Mass of reactants = Mass of products
(No mass added or removed)
Exception:
If one of the reactants or one of the products is a gas then mass can appear to be gained or lost.
What are the properties of the transitional metals?
hard and strong
high melting and boiling point
form multiple ions
for coloured compounds
7 electrons in outer shell (group 7)
shiny
ductile
malleable
sononrous
central in the periodic table
What are the properties of the alkali metals?
soft to cut
low melting and boiling points
more reactive going down group
one electron in outer shell (group 1)
ductile
shiny
malleable
sonorous
metal
Properties of metals
Hard / strong
Conduct heat / electricity
High mpts
Malleable
What are the giant covalent structures?
Diamond (SiO2)
Graphite
Graphene
Fullerene
Nanotube
Metal + oxygen = ?
Metal oxide
Metal + water =
Metal hydroxide + hydrogen
Metal + acid = ?
Metal salt + hydrogen
Properties of giant covalent structures?
High mpt + bpt (strong covalent bonds = lots of energy to overcome)
Hard and strong (e.g diamond)
Insoluble in water
What is an alloy?
Mixture (not bonded) of two or more elements, at least one of which is a metal
Why are alloys harder than pure metals?
Different sizes atoms disrupt the regular crystal lattice structure of a metal so the layers can no longer slide and the structure becomes harder
How are covalent bonds formed?
By atoms sharing electrons
Why do giant covalent structures have high melting points?
It takes a lot of energy to break the strong covalent bonds between the atoms
Why does graphite conduct electricity?
The delocalized electrons can move through the graphite
Explain why graphite is soft
Layers do not have strong covalent bonds so can slide over each other
Give two properties of graphene
Strong
Conducts electricity
Give two properties of nanotubes
High tensile strength
Conduct electricity
Why do small covalent molecules have low melting points?
Only a small amount of energy is needed to overcome the weak intermolecular forces
Describe the structure and bonding of polymers
Many identical molecules joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the chains
Why do ionic substances have high melting and boiling points?
Electrostatic attraction between positive metal ions and negative non metal ions is strong and requires lots of energy to overcome
Properties of pure metals
Malleable
High melting + boiling points
Conduct electricity
Conduct thermal energy
Why are alloys harder than pure metals
Different sizes atoms disturb the layers, preventing them from sliding over eachother
