Middle School Chemistry

Which are true about J.J. Thomson's resarch and contributions to atomic theory?
I. Discovered the nucleus
II. Use cathode ray tube
III. developed Plum Pudding Model
IV. proved atoms are indivisible

• I and II
• II and III
• I and IV
• III and IV

Which is the best definition of Mass Number for an atom?

• average mass of the isotopes of an element
• #protons-#electrons
• total # protons
• #protons + #neutrons

If you know the mass number of an isotope, what does that tell you about that atom?

• The number of protons
• The charge of the atom
• The number of neutrons
• The number of protons plus neutrons

Carbon atoms have an atomic mass of 12.011.  What does this mean?

• All carbon atoms have 6 protons and 6 neutrons in their nuclei
• The average mass of a carbon atom is 12.011 amu
• Carbon atoms typically contain 12 protons
• Neutral carbon atoms will have 12 protons and 12 electrons

Rutherford's prediction about how alpha particles would react when passing through a "plum pudding" atom:

• There should be lots of alpha particle scattering.
• There should be a tiny amount of alpha particle scattering.
• There should be absolutely no alpha particle scattering.
• The alpha particles should be absorbed and not pass through the atoms.

Which model is this?

• Dalton model
• J.J. Thomson model
• Rutherford Model
• Quantum model

In order to find the charge on an atom:

• Add proton# and electron#
• Mass#-Atomic#
• Proton#-electron#
• Mass# = charge

Identify the number of protons, neutrons and electrons in a neutral atom of carbon-14

• 14, 14, 14
• 6, 6, 8
• 6, 14, 6
• 6, 8, 6

Use a periodic table.  How many protons are in a copper-63 atom?

• 63
• 29
• 34
• depends on the isotope

Use a periodic table.  How many neutrons are in an atom of ¹⁷O?

• 17
• 8
• 9
• 25

Tags

NGSS.MS-PS1-1