Flashcards in Unit 1 Deck (57)
list 4 factors that can speed up the rate of a reaction
1. increasing concentration
2. increasing surface area - decrease particle size
3. increase temperature
4. use a catalyst
formula for rate of reaction
Average rate = change in quantity/change in time
why does that average rate of a reaction decrease over time?
the reactants are being used up so the concentration of reactants are decreasing
what is a catalyst?
a substance that speeds up a chemical reaction but is not used up by the reaction
how are elements arranged in the periodic table?
in order of increasing atomic number
how are elements in the same group similar?
- they have the same number of outer electrons
- they have similar chemical properties
- they have the same valency
describe an atom
a nucleus containing protons and neutrons with electrons in orbit
what is the mass number of an atom?
the number of protons + neutrons
what is the atomic number of an atom?
the number of protons
how do you work out the number of neutrons in an atom?
mass number - the atomic number
what is the mass of an electron?
an amount so small its not worth working out
what is the charge of an electron?
what is the mass of a proton?
1 atomic mass unit
what is the charge of a proton?
what is the mass of a neutron?
1 atomic mass unit
what is the charge of a neutron?
what are isotopes?
atoms with the same atomic number but different mass number ( they have different numbers of neutrons)
what is the relative atomic mass of an element?
the average mass of an element
what is a covalent bond?
a shared pair of electrons holding non-metal atoms together
how are atoms in a covalent bond held together?
by the attraction between the positive nuclei and the shared pair of electrons
list the 7 diatomic elements
what does diatomic mean?
two atoms covalently bonded
what shape would a molecule with the formula XY have?
what shape would a molecule with the formula XY^2 have?
what shape would a molecule with the formula XY^3 have?
what shape would a molecule with the formula XY ^4 have?
what is an ion?
an atom that has gained or lost electrons in charge ( they do this to be stable like the noble gasses)
ionic compounds are usually made from a metal and non-metal. which ion will be positively charged?
metal ion = positive
non-metal ion = negative
what is an ionic bond?
an electrostatic attraction between positive and negative ions