Who discovered the electron using the cathode ray tube experiment?
J.J. Thomson
What is the charge of a proton?
Positive
How is the mass number of an atom found?
Add the protons and neutrons. (Total number of protons and neutrons in the nucleus)
What are the vertical columns in the periodic table called?
What are the horizontal rows in the periodic table called?
Groups
Periods
What is an isotope?
Atoms of the same element with different numbers of neutrons
Who proposed that electrons move in fixed energy levels around the nucleus?
AND
Which scientist discovered the neutron?
Niels Bohr
James Chadwick
Where are neutrons found in an atom?
In the nucleus
What does the atomic number of an element represent?
The number of protons in the nucleus
What does a group tell us about an atom?
What does a period tell us?
Number of valence electrons
Number of energy levels
How many neutrons are in chlorine-35?
18 neutrons
Name Ernest Rutherford's three main conclusions from his Gold Foil Experiment.
Protons live in nucleus
Atom is mostly empty space
Which subatomic particle has the least mass?
Electron
How many neutrons are in an atom of carbon-14?
8
Which element has 3 valence electrons in the 4th energy level?
Gallium
Are carbon-12 and carbon-14 isotopes of each other? Why or why not?
Yes, because they have the same number of protons but different numbers of neutrons
Name the 4 main parts of John Dalton's Atomic Theory.
2. Atoms of the same element are identical
3. Atoms can combine to form compounds
4. When atoms combine they combine in whole number ratios by mass (Law of Constant Proportions)
How many protons does a nitrogen atom (atomic number 7) have? How many electrons?
7 and 7
What is the charge of the nucleus of an atom?
Positive, because it contains protons and neutrons
Name an element that will behave similarly to Sulfur.
Answers will vary. Any group 16 element.
Why are the masses on the periodic table decimals if we can only have whole numbers of protons and neutrons?
The masses on the periodic table are weighted averages of all the isotopes of that atom.
Choose either Thomson's or Rutherford's experiment and describe it in detail. Include what they did AND what they found.
Answers will vary.
How many protons, neutrons, and electrons in a sodium atom with a mass number of 23 and an atomic number of 11?
11 protons, 12 neutrons, and 11 electrons 11 protons, 12 neutrons, and 11 electrons
Why are atoms neutral overall?
Because they have equal numbers of protons and electrons
Which element has 2 filled energy levels and 2 valence electrons?
Beryllium
Are any of the atoms in this table isotopes of each other? Explain.
Atom Protons Neutrons Electrons
1 8 10 8
2 10 9 10
3 9 9 9
4 8 8 8
1 and 4. Same element (same # of protons) but different masses.