class exam 3

The Modern Periodic Table of Elements is arranged by

• atomic mass
• atomic number
• valence electrons
• number of isotopes

Halogens (Group 17)

• gas at room temperature, low boiling point.

• most reactive nonmetals

• The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds

• Number of protons and neutrons

What is the name of the elements that are unreactive and have a full octet?

• Halogens

• Noble Gases

• Alkali Metals

• Transition Metals

Proposed that electrons move around the nucleus in specific paths a fixed distance from the nucleus..

• Bohr

• Rutherford

• Chadwick

• Thomson

Which model was created after the discovery of the electron cloud?

• 
• 
• 
• 

What were John Dalton three contributions to atomic history?

• Created the atomic theory

• Discovered that the atom is mostly empty space

• Believed that atoms of a given element are identical

• Hypothesized that the atom is a tiny, hard sphere

• Discovered the electron

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.
What is the average mass of this element?

• 74.92 amu
• 24.97 amu
• 75.01 amu
• 74.51 amu

What does the 1.00794 stand for?

• Hydrogen
• atomic number
• atomic mass
• atomic explosion

An isotope has three forms.  30% have a mass of 4 amu, 20% have a mass of 5 amu and 50% have a mass of 3 amu.  Average atomic mass will be closest to

• 2 amu
• 3 amu
• 4 amu
• 5 amu

If an atom contains exactly three protons, then it's an atom of _____

• lithium
• gold
• nitrogen
• carbon