History of the Periodic Table
Who first organized the periodic table by increasing atomic mass?
Mendeleev
State the periodic law.
Properties repeat when arranged by atomic number.
Which group contains the noble gases?
Group 18
Does atomic radius increase or decrease down a group?
Increases
Does ionization energy increase or decrease across a period?
Increases
Which scientist reorganized the table by atomic number?
Moseley
What is a period?
A horizontal row on the periodic table.
Which group contains the most reactive metals?
Group 1 (alkali metals)
Does atomic radius increase or decrease across a period?
Decreases
Does ionization energy increase or decrease down a group?
Decreases
What evidence supported Mendeleev's predictions?
New elements were discovered with predicted properties.
What is a group?
A vertical column of elements with similar properties.
Which group contains the most reactive nonmetals?
Group 17 (halogens)
Why does the atomic radius increase down a group?
Atoms gain more energy levels.
Why does ionization energy decrease down a group?
Increased shielding and larger radius.
What major inconsistency did Moseley fix in the periodic table?
Tellurium and iodine mass-order issue
Why do elements in the same group behave similarly?
They have the same number of valence electrons.
Why are noble gases considered stable?
They have a full valence shell.
Why does atomic radius decrease across a period?
More protons pull electrons closer.
Which element has the highest ionization energy in Group 2?
Be
Why was Mendeleev’s table considered revolutionary? Name two reasons.
(1) Predicted new elements;
(2) Left open spaces;
(3) Organized elements by recurring properties.
What information does an atomic number give you?
Number of protons.
Which family contains metals with multiple oxidation states and colorful compounds?
Transition metals
Which element has the largest atomic radius: Li, C, F, or O?
Li
Which pair of trends moves in opposite directions across a period?
Ionization energy and atomic radius