Atomic Structure Flashcards
Early Greek Model (400 BC)
- Democritus
- Matter cannot be continuously subdivided
- Used the term “Atomos” (indivisible)
- The model became unpopular when Plato, Aristotle, and Socrates disagreed
Dalton’s Model
- Matter is composed of tiny particles called atoms.
- Atoms are indestructible and indivisible.
- Atoms of the same element are identical in size, mass, and properties.
- Atoms of different elements can combine into compounds.
Thomsons Plum Pudding Model
- Used a cathode ray tube for experiments
- Discovered electrons
- Said the atom was neutral due to a positive jelly-like sphere around the electrons
Rutherfords Model
- Dense, positively charged center of the atom
- Atom is mostly empty space
Bohr’s Planetary Model
- Electron orbit the nucleus in energy levels
- energy level n = 1 is closest to the nucleus
- Electrons gain energy to become excited and lose to produce light spectra
Heisenberg / Schrodinger Model
- Current model
- Wave mechanical / Cloud Model
- impossible to know the exact location of an electron
- Atom = neutral
- Protons + Neutrons = Nucleus
- Orbitals propose the probable location of e-
Proton
Positively charged particle
Neutron
No Charge
Electron
Negatively charged particle
The # of protons is called?
The atomic number
Where are protons and neutrons located?
The nucleus
Why do we need neutrons?
Without them, the protons would repel from each other
How to find the # of neutrons
mass # - atomic #
Nucleons
particles that reside in the nucleus
Weighted Average Equation
(% abundance x atomic mass) + add however many it asks
Orbitals
Most probable location for an electron
Does energy level n=1 (first orbital) have a lot of energy
No, it has the least amount. As you go outwards for orbitals you get more
Orbital electron maxium
orbital #electrons
1 2
2 8
3 18
4 32
Where to find electron configuration on the periodic table
Bottom left corner in a box of an element
Last orbital
Valence shell
Valence electrons
- Outermost
- determine the reactivity of an atom
- Nevermore than 8!
Lewis Dot diagrams
- Use # of electrons in the valence shell
- Last # for electron configuration
When taking away e- where do you take away from?
The valence shell
Nuclear charge
Charge of the nucleus
Excited-state
- Gain energy
- When an electron gains energy it moves or “jumps” to a higher energy level
- The electron configuration changes to show where electrons moved
Ground State
- An atom is in its ground state when electrons are filled into the lowest energy levels possible
- Atoms in the ground state are on the periodic table
An excited atom is
unstable and will quickly “fall” back to the ground state
The light emitted as atoms go from excited to the ground state are called:
spectral lines, atomic spectra, or bright-line spectrum
The nucleus of an atom
contains most of the mass of the atom
