Atomic Theory
Who first proposed that all matter is made of tiny, indivisible particles called atomos?
Who is Democritus?
Which subatomic particle determines what kind of element an atom is?
What is the proton?
What happens when an electron moves from a higher energy level to a lower one?
It releases energy (often as light).
Who organized the first periodic table of elements?
Who is Dmitri Mendeleev?
What modern tool can create virtual images of atoms?
A scanning transmission electron microscope (STEM).
Which law states matter cannot be created or destroyed, only changed from one form to another?
What is the Law of Conservation of Mass?
Which particle has a negative charge and orbits outside the nucleus?
What is the electron?
Which electron has the most energy: one in the 1st, 2nd, or 3rd energy level?
The electron in the 3rd energy level.
Which electron has the most energy: one in the 1st, 2nd, or 3rd energy level?
The electron in the 3rd energy level.
What lesson did Rutherford’s gold foil experiment teach about dealing with unexpected results?
Use unexpected results to ask more questions and do more experiments.
List two of Dalton’s four main points of atomic theory.
Answer: Any two:
All matter is made of atoms.
Atoms cannot be divided, created, or destroyed.
Atoms of the same element have the same properties.
Atoms combine in set ratios to form compounds.
What is the role of neutrons in atoms?
They add mass but don’t affect chemical properties; they help determine isotopes
What did Bohr say about electrons in atoms?
Electrons orbit the nucleus in fixed energy levels, like planets around the sun.
What did Bohr say about electrons in atoms?
Electrons orbit the nucleus in fixed energy levels, like planets around the sun.
What law explains why water is always H₂O, never H₃O or H₂O₂ when formed by hydrogen and oxygen?
The Law of Constant Composition.
What model described electrons as scattered throughout a positively charged “pudding”?
What is Thomson’s Plum Pudding Model?
If oxygen’s atomic number is 8, how many protons and electrons does it have?
8 protons and 8 electrons.
Why do fireworks produce different colors of light?
Excited electrons drop to lower levels and release energy as visible light.
Why do fireworks produce different colors of light?
Excited electrons drop to lower levels and release energy as visible light.
What trend occurs to alkali metal reactivity as you go down Group 1A?
Reactivity increases.
Whose gold foil experiment showed that atoms have a tiny, dense, positively charged nucleus?
Who is Ernest Rutherford?
Isotopes differ in the number of which subatomic particle?
What are neutrons?
What does the quantum mechanical (electron cloud) model describe?
Electrons move unpredictably in a cloud; their probable location is denser where the cloud is darkest.
What does the quantum mechanical (electron cloud) model describe?
Electrons move unpredictably in a cloud; their probable location is denser where the cloud is darkest.
What everyday analogy did the text use to explain the electron cloud model?
A swarm of starlings moving in the sky.