chemistry topic one Flashcards
what does the nucleus contain
protons and neutrons
what is the relative mass and electric charge of a proton
relative mass: 1
electric charge: +1
what is the relative mass and electric charge of a neutron
relative mass: 1
electric charge: 0
what is the relative mass and electric charge of a electron
relative mass: 0
electric charge: -1
what is the mass number
number of protons + neutrons
what is the atomic number
Number of Protons
OR electrons
what is the formula for relative atomic mass (Ar)
Ar = (Ar of isotope 1 x Abundance of isotope 1) + (Ar of isotope 2 x Abundance of isotope 2)
100
what is an isotope
forms of an element that have Same number of protons but different number of neutrons
describe the structure of electrons in an atom
-The 1st shell maximum of 2 electrons
-The 2nd shell maximum of 8 electrons
-The 3rd shell maximum of 8 electrons
what is an ion
An ion is an atom that gains or loses electrons
what happens when an ion looses an electron
it becomes positively charged
what happens when an ion gains an electron
it becomes negatively charged
What type of ions do metals form?
positive ions
who discovered atoms
John
Dalton
What type of ions do non – metals form?
negative ions
who Discovered electrons
JJ Thomson
what did Ernest
Rutherford discover
Atoms made of a nucleus (protons) with
electrons orbiting it.
who Discovered electron shells
Neils Bohr
what was the Rutherford scattering experiment
Alpha particles (with a positive charge) where shot at a thin gold foil most particles passed right through but some where reflected showing that an atom is made up of a small, positively
charged nucleus surrounded by electrons orbiting
who Discovered neutrons
James Chadwick
why do group 1 atoms get more reactive down the group
- Atoms get larger down the
group - Outer electron gets further
from the positive attraction of
the nucleus - Easier to lose the outer
electron as you go down the
group - Making them more reactive
why do group 7 atoms get less reactive down the group
-Atoms of each element get larger
going down the group.
- Outer shell gets further away
from the nucleus - Reduces the force of attraction
- Makes it more difficult to attract
another electron
what are chemicals in group 0 called
noble gases
why can group 0 elements not react
because they have a full outer shell
give some features of transition metals
High melting points, High densities, Shiny, Malleable, Strong, good conductors
what group are alkali metals in
group 1
what is a mixture
A mixture consists of two or more elements or compounds not chemically combined together.
what does filtration do
separates insoluble substances from a solvent e.g.
sand from water
what is Crystallisation
This technique separates a soluble substance from a solvent by evaporation
what is Simple distillation
This technique separates a liquid from a mixture by evaporation followed by condensation
what is Chromatography
This technique separates small
amounts of dissolved substances by running a solvent along absorbent paper
describe fractional distillation
a mixture is put into a fractional column which is hot at the bottom and cool at the top Substances with high boiling points condense at the bottom and substances with low boiling points condense at the top.
