Atoms And The Periodic Table Flashcards
Who made the earliest suggestion that atoms might exist in 5th century BC
Democritus
Who expanded the idea that the differences between substances were the direct results of differences in size and shape of tiny, uniform, uncuttable particles
Democritus
What are the four properties
Moist, dry, cold and hot
What are the four major elements
Water, air, fire and earth
What was the early Greek periodic table?
Air water fire earth-moist cold dry hot
Which theories were essentially philosophical and moralistic in nature with no experimental work?
Aristotle, Greek
3 early laws of chemistry
The law of definite proportions
The law of multiple proportions
The law of conservation of mass
Who was the first to believe that elements are made up of extremely small particles called “atoms”?
John Dalton
Who discovered the electrons?
J.J. Thomson
Who proved that the nucleus was surrounded by a “cloud” of negatively charged electrons?
Sir Ernest Rutherford
Who assigned atomic numbers to elements?
Moseley
Who discovered the neutron that was predicted by Rutherford?
Chadwick
“Electrons orbit at a fixed distance from the nucleus”
Niels Bohr
A set of elements in a given column going up and down the periodic table are a
Family
A set of elements in a given row across the periodic table are a
Period
Elements with 1+ ions
Alkali metals
Family of elements with highest ionization energy
Noble gases
He family with lowest ionization energy
Alkali metals
Ionization energy increases..
Right and up
Electronegativity increases..
Right and up
Atomic radius increases
Left and down
Nuclear charge increases…
Right and down
Metallic character increases…
Left and down
Nonmetallic character increases
Right and up
The least reactive family
Noble gases
Family that reacts violently with water
Alkali metals
How to calculate the average atomic mass with given isotopes?
(Mass x %) + (mass x %)
Define Ionization energy
Energy needed to take away electron
Define electro negativity
Ability to attract an electron in a chemical bond
What is the effective nuclear charge? Zeff
Zeff= atomic number - shielding electrons
Protons
Define ionic radius
Distance from the centre of atom to outer most electron in an ion
Define atomic radius
distance from nucleus to outer most electron in an atom
Non polar covalent 0-0.49
Polar covalent 0.5-1.69
Ionic 1.7+
Found by change in EN
Semi conductor non metals
B, Si, Ge, As, Se, Sb, Te
Fr is the biggest atom and most metallic
He is highest ionization energy
F is highest electro negativity
.
A cation is smaller than the neutral atom because there are less electrons than protons which causes the size to shrink
.
Anions is larger than the neutral atom because there are more electrons than protons which causes the size to expand
.
London dispersion forces
- attractions between a random dipole and an induced dipole
- preset in all molecules
- tendency of an electron cloud to distort in this way is called polarizability
- strength in London forces increase with increased molecular weight
- larger atoms have larger electron clouds which are easier to polarize (larger gives you higher melting points)
- weakest type of van der waals forces
.
Ionic bonds
- break bonds to melt ionic solid
- melting point acts as measure of bond strength
- distance between spheres affect the electrostatic attraction
.
Covalent bonds
- network solids are covalently bonded to each other
- molecular solids are held together by strong intramolecular (within) bonds but are held next to neighbouring molecules by weak intermolecular (between) bonds created by can see waals forces
.
