Atomic Models & Structure
Who proposed that all matter is made of small, indivisible particles called atoms?
John Dalton
How many electrons can the s sublevel hold?
2
The vertical columns on the periodic table are called what?
Groups or families
What is an isotope?
Atoms of the same element with different numbers of neutrons
What formula is used to find density?
D = m ÷ V
Which experiment showed that the atom is mostly empty space with a dense nucleus?
Rutherford’s gold foil experiment
What is the maximum number of electrons that can occupy a p sublevel?
6
The horizontal rows on the periodic table are called what?
Periods
What type of nuclear radiation consists of two protons and two neutrons?
Alpha radiation
Which of the following is an intensive property of matter?
Density
What did J.J. Thomson’s cathode ray tube experiment prove?
The existence of negatively charged electrons
What is the electron configuration for oxygen?
1s² 2s² 2p⁴
Which type of element is a good conductor of electricity and heat?
Metal
What happens when an excited electron returns to its ground state?
Light is emitted
If measurements are close together but far from the actual value, what are they?
Precise but not accurate
What did Bohr add to the atomic model that Rutherford’s model did not include?
Specific energy levels for electrons
What does the Aufbau principle state?
Electrons fill the lowest energy orbitals first.
Which element type shares properties of both metals and nonmetals?
Metalloids
Why does each element produce a unique line spectrum?
Each has distinct energy levels, so emitted photons have unique wavelengths.
What type of mixture has visibly different parts or phases?
Heterogeneous mixture
Compare the Thomson and Rutherford models of the atom.
Thomson’s was a uniform positive sphere; Rutherford’s had a dense, positive center surrounded by electrons.
How does the quantum mechanical model describe electrons differently from the Bohr model?
Electrons are found in regions of probability called orbitals, not fixed circular paths.
Why do elements in the same group often have similar chemical behavior?
They have the same number of valence electrons.
Which type of radiation is most penetrating and has no charge or mass?
Gamma radiation
Convert 0.0750 m into scientific notation.
7.50 × 10⁻² m