Early Theory
What does the word "atom" mean
Uncuttable, indivisible
What was Thomson's atomic model called?
Plum Pudding Model
What is the charge, location, and mass of a proton?
Positive 1, in the nucleus, 1 atm
In a neutral atom, the number of protons is equal to what?
the number of electrons
Define isotope
Atoms of the same element with different numbers of neutrons
Who was the first person to propose that matter was made up of atoms?
Democritus
Describe Rutherford's atomic model
An atom was a positively charged nucleus surrounded by negatively charged electrons circling the nucleus with no change in energy.
What is the charge, location, and mass of an electron?
Negative 1, outside nucleus, mass is negligible (approx. 0)
What charge does the nucleus have and why?
Positive. The nucleus has protons (+) and neutrons (0). Since neutrons have no charge, only the protons determine the charge of the nucleus.
What is an electron configuration?
Arrangement of electrons in the orbitals of an atom
Which philosopher believed the 4 elements were Earth, wind, water, and fire?
Aristotle
Describe Thomson's atomic model
A positively charged sphere with negatively charged particles randomly scattered throughout.
What is the charge, location, and mass of a neutron?
no charge, inside nucleus, 1 atm
What is the overall charge of an atom?
Neutral, 0, no charge. The number of electrons is equal to the number of protons, so the negative charges cancel each other out. (For example, Carbon has 6 protons (+6) and 6 electrons (-6). If you add +6 and -6, you get 0)
What does Hund's Rule state?
all orbitals of an energy level must have 1 electron before you can add a second
Who determined that an electric ray was charged particles, thus discovering the electron?
Thomson
Describe Bohr's model
Atoms have a positive nucleus with negatively charged electrons orbiting around the nucleus in fixed paths based on energy levels.
What does the atomic number of a neutral atom tell us?
the number of protons and the number of electrons if the atom is neutral
Determine the atomic number, atomic mass, #of protons, neutrons and electrons for the element Silver (Ag)
47, 108, 47p, 61n, 47e
Determine the unabbreviated electron configuration for As
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3
Who discovered that there was a dense mass near the center of an atom?
Rutherford
Describe the modern quantum mechanical model of the atom (electron cloud)
Atoms have a dense positive nucleus with electrons zooming around outside the nucleus in areas called orbitals. These are not actual paths of the electrons, but are areas where electrons are most likely to be found. Based on probability, not actual locations.
How do we determine the number of neutrons in an atom?
Subtract the atomic number from the mass number
How do we identify one element from another?
By the number of protons. Every element has a different and unique number of protons.
Determine the abbreviated electron configuration for Sm
[Xe]6s2 4f6