Subatomic Particles
Subatomic particle with a negative charge
electron
Came up with the solid sphere model of the atom and was the first chemist to prove the existence of the atom after Democritus first came up with the theory over 2000 years prior.
John Dalton (1804)
atomic number
The rows going left to right across the periodic table are called
periods
Isotopes are elements with differing amounts of
neutrons
The only subatomic particle found outside the nucleus
electron
Came up with the 'plumb pudding' model using a cathode ray to improve upon Dalton's model and proved the existence of electrons
JJ Thomson (1904)
Element with atomic number 13
Aluminum
The columns going up and down the periodic table are called
groups/families
The number of neutrons an element with 13 protons and a mass number of 27 has
14 neutrons
The two subatomic particles with a mass of 1 amu
Conducted the gold foil experiment to improve Thomson's model of an atom by discovering the positively charged protons and the mass of an atom is in the nucleus.
Ernest Rutherford (1911)
The number of protons plus the number of neutrons in an element
mass number
The group and period Silicon (Si) is in
Group 14, Period 3
Write the isotope notation for Sulfur (S) with a mass number of 33
3316S
The majority of an atom's mass is located here.
Nucleus
Improved Rutherford's atomic model by proving that electrons move around the nucleus in fixed energy levels.
Niels Bohr (1913)
Element with 38 electrons
Strontium (Sr) (atomic number 38 = 38 protons = 38 electrons)
The elements in the final group on the right side of the periodic table, Group 18, are called
The Noble Gases
Different isotopes of the same element will always have the same number of
protons/electrons
A neutral atom with 23 protons would have this many electrons. Why?
23 electrons. To maintain a neutral charge (+ = -)
DOUBLE JEOPARDY! 1000pts
1.) How did the Electron Cloud Model (1926) improve upon Bohr's model of an atom?
2.) Who discovered the neutron?
1.) Electrons move so fast and random that they do not move in fixed orbits but rather in a "most-likely" probability cloud.
2.) James Chadwick (1932)
Draw the electron configuration for a Sulfur atom
1st energy level 2
2nd energy level 8
3rd energy level 6
Explain why the elements of the same group/family have similar properties.
Each group/family have the same number of electrons in their outermost energy level, they have the same number of valence electrons.
Calculate the average atomic mass (must show correct work and proper units):
Silicon-28 (abundance: 92.21%, mass: 27.977 amu)
Silicon-29 (abundance: 4.70%, mass: 28.976 amu)
Silicon-30 (abundance: 3.09%, mass: 29.974 amu)
28.11amu
Si-28: 0.9221 x 27.977amu = 25.82amu
Si-29: 0.0470 x 28.976amu = 1.36amu
Si-30: 0.0309 x 29.974amu = 0.93amu
25.82amu + 1.36amu + 0.93amu = 28.11