Unit 2 Review - Structure of an atom and periodic table

2 rows beneath the main periodic table

• Lanthanide

• Lanthanide and Actinide

• Lanthanide and Hydrogen

• Actinide and Hydrogen

As of 2025, how many elements are there?

• 100

• 110

• 115

• 118

How are the elements arranged on the periodic table today?

• By atomic mass

• By number of electrons

• By atomic number

• By alphabetic order

How did Mendeleev arrange the elements?

• by alphabetical 

• by density

• by melting point

• by atomic mass

 In the modern periodic table elements are arranged by:

• atomic mass

• valence electrons

• atomic number

• number of isotopes

  Why were there blank spaces left in Mendeleev's periodic table?                                             

•  He didn't know what to put there.

•   Undiscovered elements not yet known.

• Multiple elements could have fit

• He forgot to add the elements in

Each column in the periodic table is called a 

• period
• group
• cluster
• unit

Elements which are shiny, conduct electricity and heat are called

• metal
• nonmetal
• metalloid
• nonexistent

The atoms along the staircase are called 

• metals
• nonmetals
• metalloids
• noble gases

Tags

NGSS.MS-PS1-1

How many protons are in this element?

• 79
• 196
• 117
• Cannot be determined

Tags

NGSS.MS-PS1-1