Table's Origins
Who organized the first periodic table based on atomic mass?
Dmitri Mendeleev
What are the three main classes of elements?
Metals, nonmetals, and metalloids
What is a periodic trend?
A predictable pattern in element properties that repeats across the table.
In which section of the periodic table are transition metals located?
Groups 3–12
Which group contains the most reactive nonmetals?
Group 17 (Halogens)
Periods and Groups/Families
Name one physical property that distinguishes metals from nonmetals.
Metals are good conductors (nonmetals are poor conductors).
Which trend increases from left to right across a period?
Electronegativity or ionization energy
What are the two inner transition metal series called?
Lanthanides and actinides
Which group contains noble gases that are inert due to full valence shells?
Group 18
What observation led Mendeleev to leave gaps in his table?
He predicted undiscovered elements that would fit the pattern.
What makes metalloids unique?
They have properties of both metals and nonmetals.
Which trend increases from top to bottom in a group?
Atomic radius
What is an alloy?
A mixture of metals or a metal with another element.
Name one important element from Group 14 and describe its use.
Silicon – used in electronics and computer chips.
What is the Periodic Law?
When elements are arranged by increasing atomic number, their properties repeat in a regular pattern.
Which group of metals reacts violently with water?
Alkali metals (Group 1)
Define ionization energy.
The energy required to remove an electron from an atom.
Give one example of an important transition metal and its use.
Iron – used in steel; Copper – electrical wiring; Chromium - chrome. (ans vary)
Compare the reactivity and abundance of elements from Groups 13–18.
Reactivity decreases as you move toward Group 18; abundance varies
Why was Mendeleev’s table revolutionary for chemistry?
It accurately predicted the properties of elements not yet discovered, like gallium and germanium. (ans vary)
Compare the reactivity of alkali metals and alkaline earth metals.
Alkali metals are more reactive because they lose one electron more easily.
Explain the difference between ionization energy, electron affinity, and electronegativity.
Ionization energy → energy to remove an electron
Electron affinity → energy released when gaining an electron
Electronegativity → attraction for shared electrons in a bond
Describe a key difference between lanthanides and actinides.
Lanthanides are mostly stable and used in magnets; actinides are mostly radioactive.
Name one element from each of the following and state a major use:
Group 13, 15, 17
(answers vary)