ATOMIC STRUCTURE Flashcards
What experiment lead to the current model of the atomic structure?
Rutherford experiment with alpha particles shot at a thin gold foil resulted in the Rutherford model of the atom (Orbital Model). This model depicted an atomic model with nearly all its mass, and positive charge, in a central nucleus about 10,000 times smaller than the atom itself
Describe the Bohr and quantum mechanic model of an atom
The Bohr Model is a planetary model in which the negatively charged electrons orbit a small, positively charged nucleus
The quantum mechanical model of the atom uses complex shapes of orbitals (sometimes called electron clouds), volumes of space in which there is likely to be an electron. So, this model is based on probability rather than certainty
Describe an orbital in terms of probability
An orbital, or ‘electron cloud’ is the best estimate of an electrons location at a point in time
Describe an orbitals and subshells
each orbital is a region of space and can hold up to 2 electrons with opposite spins
each subshell is a collection of orbitals
Orbitals that are present in the first 4 electrons shells
n=1, 1 subshell, s
n=2, 2 subshells, s, p
n=3, 3 subshells, s, p, d
n=4, 4 subshells, s, p, d, f
shells fill from lower energy level upwards, when there is a set of orbitals with equal energy, they take turns ‘filling up’ before any of them becomes completely filled (Hund’s rule)
Describe what happens when an electron absorbs energy
When electrons collide with and absorb energy, they can attain higher energy levels. When they drop to lower, more stable energy levels, energy is emitted. If the released corresponds to the energy of visible light, the emission produces a colour that can be detected by the human eye
Describe a wavelength
A wavelength is the term given to the distance between a crest of one wave and the next; it provides a way to distinguish between different types of electromagnetic radiation
Example: when a very high voltage is applied to a gas discharge tube, the gaseous atoms are ‘excited’ and give out light of specific wavelengths
Describe the difference between a continuous spectrum and a line emission spectrum
A continuous spectrum consists of all wavelengths within a certain range. In contrast, a line spectrum only consists of a few wavelengths. This spectrum is made of a few colored lines on a dark background. The lines in spectra are caused by electrons moving in between energy levels
What are the shapes of the s and p orbitals?
S orbital is spherical
P orbital is dumbbell
