Developed the periodic table based on the atomic mass

• Mendeleev

• Moseley

Created the first periodic table

• Mendeleev

• Moseley

Organized elements by their atomic number

• Mendeleev

• Moseley

Developed the modern-day periodic table

• Mendeleev

• Moseley

horizontal rows

• periods

• groups

have the same energy levels

• periods

• groups

vertical columns

• periods

• groups

families

• periods

• groups

Tags

NGSS.MS-LS4-2

elements have the same number of valence electrons

• periods

• groups

elements have similar chemical properties

• periods

• groups