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Atomic Structure and Periodicity - Coggle Diagram
Atomic Structure and Periodicity
subatomic particles;
protons
neutrons
electrons
protons
located in the nucleus
positively charges
atomic mass of 1
neutrons
atomic mass of one
no charge
located in the nucleus
electrons
located in shells (energy levels)
1 to 7
there are four main shells 1, 2, 3, 4 OR K, L, M, N
max number per shell is determined by 2n^2
Subshells
according to the main shell number is the amount of sub-levels there are
sub shell level are called; s, p, d, f
s = 2 electrons, p = 6 electrons, d = 10 electrons, 14 = electrons
Orbitals
a region in space where two electrons are likely to be found
electrons are negative so they must repel each other = electrons will spin in opposite directions to allow them to be in the same orbital
Pauli Exclusion Principle
"each sub-level consists of ORBITALS and each orbital can hold 0, 1, or 2 electrons"
max of two electrons per orbital
Aufbau Principle
electrons fill lower-energy subshell first before filling higher-energy ones
Hunds Rule
every orbital in a subshell is singly occupied with one electrons before any one orbital is doubly occupied, unpaired electrons in orbitals have the same spin
negatively charged
1/8 mass of the protons/neutrons
atomic number (Z) is the number of protons. they are
equal
to the number of electrons in the NEUTRAL atom
Mass Number (A) is the sum of the number of protons and neutrons
Isotopes
are atoms of the SAME element with the SAME atomic number but DIFFERENT mass numbers (different number of neutrons)
they have the same chemical properties BECAUSE the SAME NUMBER of electrons (electrons are involved with chemical reactions)
they have slightly different physical properties BECAUSE the number of neutrons hence the different masses
isotopes with FEW neutrons will have;
lower mass
faster rate of diffusion
lower density
lower melting/boiling points
Relative Atomic Mass
all atomic mass is relative to the mass of carbon-12 because they are standard in all nonliving and living things
RAM is the weighted mean of the naturally occurring isotopes
Symbol is
Ar
Radioisotopes
they are radioactive isotopes
can be useful
Mass Spectrometer
is an instrument used;
to measure relative masses of isotopes
to find relative ABUNDANCE of the isotopes in a sample of elements
Vaporization
sample has to be in GASEOUS FORM
if solid or liquid, heater will
vaporize
it
Ionization
sample is bombarded by a stream of high-energy electrons which 'knock; an electron from the atom to form a positive ion
Acceleration
electric field is used to accelerate positive ions towards magnetic field through a slit to form a beam of ions
Deflection
ions are deflected into magnetic field
amount of deflection is greater when;
mass of ion is less
charge of ion is greater
velocity of ion is less
strength of magnetic field is greater
Detection
cause electrons to be released in an ion-current detector
records to convert the current into a peal which is shown in the mass spectrum
Emission and Absorption Spectra
Frequency
is the amount of waves per second
Wavelength
is the distance from one crest to another
High Energy
= shorter wavelengths, many frequencies
n = 1 has high energy (colour violet and ultra violet waves)
Low Energy
= longer wavelengths, less frequencies
n= 2/n=3 has low energy (color red has longer wavelength than color violet. infrared waves have low energy)
Periodicity
Atomic Radius in a Group
radius INCREASES down a group
electron cloud does not have definite shape
larger atom because of the increasing mass requiring more electrons and energy levels
Atomic Radius in a Period
radius DECREASES left to right on a period
atoms have SAME ENERGY LEVEL while the number of PROTONS INCREASE therefore the attractive forces between electrons and protons cause them to suck in hence smaller radius
Size of isoelectronic ions
positive ions are smaller
elements or ions with same number of electrons are called ISOELECTRONIC
Ionic Radius
Cations
form by losing electrons and are smaller (metals tend to lose, creating then smaller which make them a smaller species)
Anions
form by gaining electrons and are larger (non-metals tend to gain, creating them bigger which make them a larger species )
Electronegativity
tendency for an atom to attract a shared pair of electrons when it is covalently bonded to another atom
big electronegativity means it pulls the electrons towards
Group Trend
DECREASES down a group
very attracted to nucleus at the top on the table
less attractive to nucleus because of the number of electrons blocking the nucleus
they are loosely held caused by the SHIELDING EFFECT
Period Trend
INCREASES from left to right across period
left of the periodic table have less valance electrons = LOW electronegativity (lose electrons)
right of the periodic table have more valance electrons = HIGH electronegativity (gain electrons)
Effective Nuclear Charge (shielding)
average charge felt by an individual electron in an atom cause of shielding effect of inner electrons
Zeff = Z - S / mass No. - inner shell electrons
Ionization Energy
'is the amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state'
ionization is a measure of how tightly the outer-shell electrons are held in an atom
METALS = LOW ionization
NON-METALS = HIGH ionization
DECREASES down a group because of the reducing Nuclear Charge attraction
INCREASES right across period because of the increasing Nuclear Charge attraction
when their are PAIRED electrons in orbitals, REPLUSION IS GREATER = low ionization
Melting Point
Group 1/Alkali Metals
melting point DECREASES down the group because of the weaker attraction held
less heat is needed
Group 7/Halogens
melting point INCREASES down the group because there are DIATOMIC
the extra electrons make the molecules bigger therefore need more energy to break the intermolecular attraction
Metal and Non-Metal Oxides with Water
METALS + WATER = STRONG BASES (hydroxides) ph >7
NON-METALS + WATER = ACIDIC OXIDES (acids) ph < 7
metallic nature decrease left to right across a period (atoms that want to lose electrons and form positive ions)
