Ch4 (Models of the Atom) Flashcards
(35 cards)
Who first argued that all matter is continuous?
Greek philosopher Aristotle
Who first argued that matter is discontinuous?
Democritus
According to Democritus, what is atomos?
The point when matter can no longer be subdivided
Who published the first atomic theory?
John Dalton (1803)
What are the 5 postulates of Dalton’s Atomic Theory?
- an element is composed of indivisible+indestructible atoms
- all atoms are identical/have same properties
- Atoms of different elements combine to form compounds
- compounts contain atoms in small whole-number ratios
- Atoms can combine in more than one ratio to form different compounds
What was Thomson’s model of the atom called, and how was it discovered?
The Plum Pudding Model; it was discovered using cathode rays
What did Thomson discover?
The electron
What did the Plum Pudding model propose?
That electrons were distributed evenly through a positive sphere
Who discovered the charge of an electron?
Robert Millikan
Who used thin gold foils to test the Plum Pudding model?
Ernest Rutherford
What three things did Rutherford notice using his gold foil experiment?
- The atom is largely empty (Most alpha particles passed through the foil)
- The center of an atom is the dense atomic nucleus (the alpha particles bounced back)
- The atomic nucleus contains the protons (the alpha particles would bend around it)
Who discovered the atomic nucleus?
Rutherford
Who discovered Neutrons (n^0)?
James Chadwick
Draw a sample Atomic Notation
Does it include the Atomic Mass (A), the Atomic Number (Z) and Sy (Symbol)?
Isotopes
Atoms of the same element with a different numberof neutrons
Atomic Mass
The weighted average mass of all known isotopes of the element (takes into account the percent abundance)
Wavelength
The distance the light wave travels in one cycle
Frequency
The number of wave cycles completed each second
At what speed does light travel?
3.00 x 10^8 m/s
Draw an example of the radiant energy, or continuous, spectrum
Does it include a color gradient and/or an example of the wavelengths/frequencies?
What is the visible spectrum?
All the wavelengths we can see, ranging from 400 to 700 nm
Quantum Concept
Energy is present in small, discrete bundles (imagine a ball rolling down the stairs rather than a ramp)
Who speculated that electrons orbit about the nucleus in fixed energy levels?
Neils Bohr
How do emission line spectrums help ID elements?
The emission line spectrum of each element is unique
