People
Classified some elements into groups of three
Who is Johann Dobereiner?
When elements are arranged by increasing atomic number, there is a periodic repetition of their properties
What is periodic law?
Groups 1, 2 and He
What are s-block elements?
Alkali metals
What is group 1A?
Decreases left to right
What is atomic size period trend?
Published a table of elements organized by increasing atomic mass in 1869
Who is Dmitri Mendeleev?
Number of protons and neutrons
What is atomic mass?
Groups 13-18
What are p-block elements?
Alkaline earth metals
What is group 2A?
Increases down
What is atomic size group trend?
"father of the modern periodic table"
Who is Mendeleev?
Number of protons in the nucleus of an atom
What is atomic number?
Groups 3-12
What are d-block elements?
Transition metals
What is group B?
Generally increases up and to the right
What is electronegativity trend?
Suggested the elements be arranged in "octaves"
Who is John Newlands?
Horizontal rows on the periodic table
What is a period?
Inner transition metals
What are f-block elements?
Haloegns
What is group 7A?
Increases down and to the left
What is atomic size and ionic size?
Arranged elements by increasing atomic number
Who is Henry Moseley?
Three classes of elements
What is metals, nonmetals, and metalloids?
The energy sub-level being filled
What determines the blocks?
What is group 8A?
Energy level, charge on nucleus, and shielding effect
What three factors influence periodic table trends?