How did chemists change Mendeleev’s periodic table in the early 1900s?

• They included chemical properties such as bonding power

• They used atomic number instead of atomic mass to organize the elements

• They used atomic mass instead of atomic number to organize the elements

• They included physical properties such as melting point and density

The vertical (up and down) columns in the Periodic Table are called

• groups

• towers

• periods

• atomic numbers

The Modern Periodic Table of Elements is arranged by

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

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Sodium (Na) is found in period 

• 3
• 2
• 4
• 1

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Sodium (Na) is found in group 

• 1
• 2
• 3
• 4

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The atomic number tells you what? READ THE ANSWERS CAREFULLY

• only the number of electrons

• only the number of protons

• only the number of neutrons

• the number of both electrons and protons in an atom.

What does the atomic mass tell you? 

• Basically,the number of electrons and protons
• The number of neutrons
• Basically, the number of protons and neutrons
• The number of protons.

What does the 6 represent?

• atomic mass
• atomic number
• element name
• chemical symbol 

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What does 12.011 represent?

• atomic mass
• atomic number
• element name
• chemical symbol 

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What does the C represent?

• atomic mass
• atomic number
• element name
• chemical symbol 

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