Atomic Structure Review

How many protons are in an atom with an atomic number of 20, an mass number of 45, and a charge of +2?

• 20
• 10
• 2
• 18

How many neutrons are in an atom with an atomic number of 20, an mass number of 45, and a charge of +2?

• 20
• 25
• 2
• 18

How many electrons are in an atom that has an atomic number of 34, an atomic mass of 74 and a charge of -2?

• 34
• 36
• 2
• 40

Which particle does not contribute significant mass to the atom?

• Proton
• Neutron
• Electron
• Nucleus

What scientist is best known for his "Plum Pudding" model of the atom?

• J.J. Tomson
• Ernest Rutherford
• John Dalton
• Democritus

What scientist is best known for his gold foil experiment?

• J.J. Tomson
• Ernest Rutherford
• John Dalton
• Democritus

Who is the first scientist to think that the atom was the smallest unit of matter (that if you kept cutting things smaller, you would reach a point of not being able to cut any smaller anymore)?

• J.J. Tomson
• Ernest Rutherford
• John Dalton
• Democritus

The mass number of an element that has 18 protons, 18 electrons, and 19 neutrons is _____.

• 18
• 19
• 36
• 37

If the number of electrons in an atom changes you make a(n) __________________.

• ion
• isotope
• new element
• isomer

How many neutrons does uranium-239 have

• 92
• 147
• 239
• 331