Periodic Table History
Mendeleev mostly arranged elements by increasing atomic mass, but he made exceptions when the __________ of elements didn't fit the pattern.
Properties
Atomic radii ______ across a period.
Since the first energy level contains only the 1s sublevel, the number of elements in this period is ____.
2
The electrons available to be gained, lost, or shared in the formation of chemical compound are called____.
Valence electrons
These alkali metals are highly reactive, soft, easy to cut with a knife, and aren't found in nature in their pure form.
What are group 1 elements?
For elements in groups 1, 2, and 18, the increase in atomic number for successive elements follows the pattern 8, 8, 18, 18. What number follows 18 in this pattern?
32
Electronegativity_______ down a group.
What is decrease?
Identify the period, block, and group of the following configuration: [Ar]3d24s2
fourth period, d-block, and group 4
The energy change when an electron is acquired by a neutral atom is called______.
Electron affinity
This group of elements has two valence electrons.
What are group 2 elements?
Moseley arranged elements in order of increasing_______.
Atomic number
Atomic radii _______ down a group.
Lanthanides
The energy required to remove one electron from an atom is called_____.
These halogen, nonmetal elements react vigorously with metals to form salts.
What are group 17 or 7A elements.
This unique characteristic of Mendeleev's periodic table made it possible for undiscovered elements to be included at a later date.
What is gaps?
As the atomic number increases within a group of elements, the atomic radius_________.
Increases
These elements make up groups 1-2 and groups 13-18.
What are main group elements?
The measure of the ability of an atom to attract electrons from another atom is called______.
Electronegativity
These noble gas elements are exhibit great stability and low reactivity.
What are group 18 elements?
This law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.
What is the Periodic Law?
For each successive electron removed from the atom, does the ionization energy decrease or increase?
Increase
Elements whose atoms contain partially filled d sublevels when they are in the ground state are called_____ metals.
Transition
One-half the distance between the nuclei of identical atoms that are bonded together is the _______.
Atomic radius
This group of elements have 6 valence electrons in their outer most energy level.
What are group 16 elements?