The Atom Flashcards
What does the Mass number tell us about an isotope?
The number of protons and neutrons in the nucleus
What does the Atomic number tell us?
The number of protons in the nucleus
Where are protons and neutrons found?
In the nucleus
How would we calculate the number of neutrons in a isotope?
Mass number - Atomic number
Give the relative charge and relative mass of protons, neutrons and electrons
Proton- charge +1, mass 1
Neutrons- charge 0, mass 1
Electrons- charge -1, mass 1/1840
What did Ernest Rutherford discover?
Found that most of the mass and all of the positive charge was in a tiny central nucleus
What did Henri Becquerel discover?
Radioactivity, showing that particles come from inside the atom, therefore atoms are divisible
What did JJ Thompson discover?
The electron, and that is negatively charged, that all electrons from an atom are the same.
Suggested the precedes of protons to balance charge, suggested plum pudding model
What did John Dalton discover?
Suggested elements were made of invisible atoms,
Same elements = same mass
What did Robert Boyle discover?
Proposed there ewe substances that could be made simpler- chemical elements
electrons are arranged in energy levels and sub-levels, what letters are given to the sub-levels?
s,p,d,f
write an equation for the first ionisation energy of sodium?
Na(g) –> Na+(g) +e-
what is the electronic configuration for vanadium? (periodic table needed)
1s2, 2s2, 2p6, 3s2, 3p6,3d3, 4s2
which sub-shell fills first- 4s or 3d?
4s
what is the maximum number of electrons held in each of the s, p ,d sub-shells?
s-2
p-6
d-10
z for krypton is 36, what is the electronic configuration? (periodic table needed)
1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p6
there are two isotopes of chlorine, Cl-35 (75%) and Cl-37 (25%), show that the R.A.M of chlorine is 35.5
(35 x 75) + (37 x 25)
____________________
100
=35.5
how do we work out the relative atomic mass of an element?
add up (mass x abundance) for each isotope and then divide by total abundance
(mass x Abundance
__________________
total abundance
what happens to first ionisation energies as we move left to right along the period? why?
it increases
because nuclear charge increases but shielding remains the same
what is an atomic orbital?
a volume f space that an electron (or pairs of electrons) fill
what is an energy level?
“a shelll”
a collection of electrons with similar energy. the first ‘shell’ contains 2, the second 8 and the third 18 electrons.
when moving right to left across the period 3, what exceptions are there for ionisation energy?
Auminium- because the electron is being moved from3p, which has a slightly higher energy level than 3s.
Sulfur- because there are two electrons in one of the 3p orbitals and so there is repulsion between them
what can we say about the spin of pairs of electrons?
paired electrons will have opposite spin
what is the rule for electron pairing in orbitals?
electrons will fill in singly within the same sub-shell, before they pair (because they repulse each other)
write the equation for the second and third ionisation energies of sodium
Na+(g) –> NA2+(g) + e-
NA2+(g) –> NA3+(g) +e-
define first ionisation energy
the energy required to remove one mole of electrons from one mole of atoms, in the gaseous state
how are electrons removed from atoms?
ioniation, the atoms are hit with a beam of electrons from an electron gun
what is an isotope
atoms of the same element, with the same number of protons and electrons, but a different number of netrons
what does letter A stand for?
mass number
what does the letter Z stand for?
atomic number
define second ionisation energy
the energy required to remove one mole of electrons from one mole of atoms, with one positive charge, in the gaseous state
when thinking about electrons what should we thnk
S- shielding A- attraction (to) N- necleus D- distance (of outer shell) E- elctrons
what does ionic bonding happen between
metal and non-metal
what properties do ionic compounds have
melting points
strong force between oppositely charged ions
molten when dissolved