History
Who arranged the periodic table of elements in order of atomic number?
Henry Moseley.
What are the vertical columns of the periodic table called?
Groups
Explain why atomic radius decreases across a period left to right.
The number of protons increases, pulling electrons closer to the nucleus.
Name the three classes of elements.
Metals, nonmetals, and metalloids.
Who is attributed with the idea of arranging the known elements?
Dmitri Mendeleev.
What are valence electrons?
Electrons found in the outermost energy level of atoms.
What is the trend for reactivity for the alkali metal group?
Reactivity increases going down the group.
Which of these atoms is largest: nitrogen, phosphorus, or arsenic?
Arsenic.
What do elements in the same periodic group have in common?
Same valence configuration and similar chemical properties.
What do elements in the same periodic period have in common?
Same number of occupied energy levels (principle energy levels).
As you move left to right across a period, what happens to ionization energy?
Ionization energy increases.
Which side of the periodic table houses most of the nonmetals?
The right side
Who predicted that empty spaces on his periodic table represented undiscovered elements?
Dmitri Mendeleev.
How many elements are in a period where only the s and p sublevels are filled?
8
Which atom would it take more energy to remove its first electron, sodium or aluminum?
Aluminum.
List the following atoms in order of decreasing electronegativity: Cl, K, & Zn.
Cl, Zn, K.
What is the periodic law?
There is a periodic repetition of physical and chemical properties of the elements when they are arranged in order of increasing atomic number.
Identify the sublevels in a period that contains 32 elements.
s, p, d, f.
Why is the third ionization energy of magnesium so much greater than the second?
After removing two electrons, magnesium has a full outer energy level.
What is the most electronegative element?
Fluorine.