Atomic Structure Flashcards
Who is the father of modern chemistry?
Antoine Lavoisier
- Proposed the law of conservation of mass
- Proposed combustion
Define “Law of Conservation of Mass”
Total mass of a substance present after a chemical reaction is the same as the total mass of substances before a reaction
total mass of reactants = total mass of products
Define “Law of Definite Proportions”
Proposed by Joseph Proust, this states that all samples have same proportions by mass of constituent elements regardless of source
This gave way to the identity of substances
Define “Law of Multiple Proportions”
Proposed by John Dalton, first empirical evidence on the existence of atoms. He managed this through the use of gases
We can observe the formula of two elements based on proportion
Development of the Atomic Model:
Who is Democritus?
“Atomos” - Proposed that matter is composed of indivisible particles called atoms
Development of the Atomic Model:
Who is John Dalton?
Proposed basic atomic theory
- Each element is composed of atoms
- Atoms of different elements are different from each other
- atoms of one element cannot become another
- atoms combine to form compounds
- hard sphere model - this indivisible sphere is the smallest building block in the world
Development of the Atomic Model:
Who is JJ Thomson?
- Discovered electrons by analysing cathode rays - cathode ray tube experiment
- Measured mass/charge ratio for electrons
- Proposed the plum pudding model of an atom (electrons are randomly arranged on a positively charged sphere)
Development of the Atomic Model:
Who is Robert Milikan?
- Performed oil drop experiment to determine electron charge
Development of the Atomic Model:
Who is Ernest Rutherford?
- conducted the gold foil experiment
- Discovered that the atom was mostly empty space with positively charged center called the nucleus
What are Isotopes?
Atoms of the same element (same # protons) but different # of neutrons thus a different mass
What are isotones?
Atoms with the same number of neutrons but different number of protons
What are Isobars?
Atoms with the same mass but different atomic number
There are 3 naturally occuring isotopes of Mg. Their masses and percent natural abundances are 23.985 amu, 78.99%; 24.986 amu, 10.00%; and 25.982 amu, 11.01%. Calculate weighted average atomic mass.
Average atomic mass = summation [(isotope mass) x (fractional abundance)]
24.305 amu
Define amplitude, wavelength, and frequency
Amplitude (A) - vertical distance from midline of wave to the peak or trough
Wavelength (lambda) - horizontal distance between identical points (peak or trough) on successive waves
Frequency (v) - number of waves that pass through a particular point in 1 second (Hz = 1 cycle/s)
What is EM Radiation?
Electromagnetic radiation is the speed of the wave that travels at the speed of light in a vacuum (c=lambda x v)
