Chemistry Paper 1 Flashcards
What does the atomic number tell you?
The number of protons in an atom.
What are isotopes?
Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons.
Describe the ‘plum pudding model
Atom shown as a ball of positive charge with electrons stuck in it.
What happened during the alpha particle scattering experiment conducted by Ernest Rutherford and what discoveries were made.
Most particles went through the gold sheet, but some were deflected more than expected at the time, and a small number were deflected backwards.
Rutherford, with his evidence, came up with the nuclear model of the atom. In this, there’s a tiny positively charged nucleus at the centre, where most of the mass is concentrated. A ‘cloud’ of negative electrons surrounds this nucleus - so most of the atom is empty space.
What does the mass number tell you?
The total number of protons and neutrons in the atom.
What did Niels Bohr discover?
Bohr proposed that electrons orbit the nucleus in fixed shells and aren’t anywhere in between. Each shell is a fixed distance from the nucleus.
What did James Chadwick discover?
A
The existence of neutrons in the nucleus.
Describe The Table of Elements made by Dmitri Mendeleev
50 known elements arranged in order of atomic mass but some were switched depending on their properties. Gaps were left in the table to make sure that elements with similar properties stayed in the same groups and to leave room for undiscovered elements.
State the physical properties of metals
Strong (hard to break), but are malleable, good conductors of heat and electricity, high melting and boiling points.
State the physical properties of non-metals
Dull-looking, more brittle than metals, aren’t always solid at room temperature, don’t generally conduct electricity and often have a lower density.
State some properties of transition metals
Transition metals can have more than one ion/charge. They are often coloured and so compounds that contain them are colourful. Transition metal compounds often make good catalysts.
Describe the trends for the alkali (Group 1) metals as you go down the group
More reactive than transition metals. Much less dense, strong and hard than transition metals and have much lower melting and boiling points.
Describe the trends as you go down Group 7 (halogens)
The halogens become less reactive, have higher melting and boiling points, higher relative atomic masses.
State some properties of halogens
They are poisonous, coloured vapours that exist as molecules which are pairs of atoms.
What is a molecule
Two or more non-metal atoms bonded together (can be same type of atom).
Why does the boiling point increase as you go down Group 0 elements (noble gases)?
The increase in boiling point is due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome.
Describe some properties of noble gases (Group 0 elements)
Group 0 elements are inert, colourless gases with full outer shells.
What are ions?
Ions are charged particles.
Which groups are the most reactive?
Group 1, 2, 6 and 7.
By what forces, are oppositely charged ions strongly attracted to one another?
By electrostatic forces
What are the properties of ionic compounds?
High melting and boiling points (strong bonds between ions require a lot of energy to break), don’t conduct electricity when in solid form (ions are held in place) but conduct electricity when molten as ions are free to move.
By what forces, are positively charged nuclei of bonded atoms attracted to the shared pair of electrons in covalent bonding?
By electrostatic forces.
What are the properties of simple molecular substances?
Atoms within molecules are held together by very strong covalent bonds. By contrast, the forces of attraction between these molecules are very weak so they have low melting and boiling points and don’t conduct electricity as they’re not charged.
What type of bonds are there in polymers
Covalent bonds
What are properties of giant covalent structures?
Very high melting and boiling points due to strong covalent bonds between atoms. They don’t conduct electricity as they don’t contain charged particles (however graphite can conduct electricity due to the presence of one delocalised electron per carbon atom).
What are polymers?
Long molecules that consist of long chains of repeating units.
Give three examples of giant covalent structures
Diamond, graphite and silicon dioxide
