Unit 4 Vocabulary

Question 1

Periodicity

Answer 1

Periodicity means a trend or a pattern of repeating and in genuine order.

Eg. Our periodic table is so arranged that on moving from left to right the atomic size decreases and on going down it increases so basically it is arranged from smallest to biggest down the group.

Same as electronegativity and many more increases from left to right and decreases from top to bottom in a particular manner.

Question 2

Period

Answer 2

A period is a horizontal row of the periodic table.

Question 3

Group

Answer 3

A column in the periodic table of chemical elements.

Question 4

Pauli Exclusion Principle

Answer 4

No two electrons in the same atom can have identical values for all four of their quantum numbers.

1) no more than two electrons can occupy the same orbital and (2) two electrons in the same orbital must have opposite spins

Question 5

Lewis Electron Dot Diagram

Answer 5

Diagrams that describe the chemical bonding between atoms in a molecule. They also display the total number of lone pairs present in each of the atoms that constitute the molecule.

Question 6

Noble Gases

Answer 6

Any of a group of rare gases that include helium, neon, argon, krypton, xenon, and sometimes radon and that exhibit great stability and extremely low reaction rates.

Question 7

Transition Elements

Answer 7

Transition elements are unique in that they can have an incomplete inner subshell allowing valence electrons in a shell other than the outer shell. Other elements only have valence electrons in their outer shell. This allows transition metals to form several different oxidation states.

Question 8

Lanthanides

Answer 8

Any of the series of fifteen metallic elements from lanthanum to lutetium in the periodic table.

Question 9

Actinides

Answer 9

Elements with atomic numbers from 90 to 103 following element Actinium.

They include naturally occurring elements of thorium, protactinium and uranium and eleven transuranic i.e., artificially produced by nuclear reactions. Nevertheless, all actinides are radioactive.

Question 10

Octet Rule

Answer 10

Dictates that atoms are most stable when their valence shells are filled with eight electrons.

Question 11

Metal

Answer 11

Any of a class of substances characterized by high electrical and thermal conductivity as well as by malleability, ductility, and high reflectivity of light.

Question 12

Nonmetal

Answer 12

Elements that form negative ions by gaining electrons during chemical reactions. Thus, they are electronegative elements with high ionization energies. In general, non-metals are brittle, dull, and poor conductors of heat and electricity. They tend to have lower melting points than metals.

Question 13

Metalloid

Answer 13

An element (e.g. arsenic, antimony, or tin) whose properties are intermediate between those of metals and solid nonmetals or semiconductors.

Question 14

Alkali Metals

Answer 14

any of the six chemical elements that make up Group 1 (Ia) of the periodic table—namely, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The alkali metals are so called because reaction with water forms alkalies (i.e., strong bases capable of neutralizing acids).

Question 15

Alkaline Earth Metals

Answer 15

The elements in the second group of the periodic table, starting with beryllium and ending with radium.

Question 16

Halogens

Answer 16

A chemical element that forms a salt when it reacts with metal.