Lesson 3

Question 1

Periodic table of elements

Answer 1

A system of organization for the elements. Elements are positioned based on their atomic number and type. The periodic table of elements lists information about each element, including atomic number, atomic mass, and symbol.

Question 2

Atomic number

Answer 2

The number of protons contained in an atom. Each element has its own invariable atomic number. The atomic number is often used to identify elements

Question 3

Atomic mass

Answer 3

The total average number of protons and neutrons in an atom. A measurement of the mass of an atom can be estimated by calculating the total number of protons and neutrons in an atom’s nucleus. Atomic mass is measured in atomic mass units.

Question 4

Symbol

Answer 4

the letter or abbreviation for the element

Question 5

Periods

Answer 5

The name for a row in the periodic table of elements. Periods are determined by the highest energy level where electrons can be found in an atom of that element. elements found in the lower periods of the periodic table have much higher energy than those found in the upper periods

Question 6

Groups

Answer 6

The name for a column in the periodic table of elements. Groups are generally divided based on the number of valence electrons in an atom of the element. In the United States, groups are numbered with Roman numerals and capital letters, e.g I-VIIIA and I-VIIIB

Question 7

Metal

Answer 7

In the periodic table of elements, one of the three broad categories into which elements are classified based on their properties. Metals include the alkali metals (found in group IA), the alkaline earth metals (IIA), and the transition and inner-transition metals (group B). Metals are good conductors of electricity and have a metallic sheen. They can be molded or stretched without breaking.

Question 8

Nonmetal

Answer 8

In the periodic table of elements, one of the three broad categories into which elements are classified based on their properties. Nonmetals include hydrogen, the halogen gases (found in group VIIA), the chalcogens (VIA), and the novel gases (group VIIIA). Nonmetals, in a solid form, do not gleam, are poor conductors, and tend to be fragile.

Question 9

metalloid

Answer 9

In the periodic table of elements, one of the three broad categories into which elements are classified based on their properties. Metalloids are also called semimetals or semiconductors. the semimetals include boron (5), silicon (14), germanium (32), arsenic (33), antimony (51), tellurium (52), polonium (84), and astatine (84). Metalloids sometimes have the metallic gleam of metals but are more fragile. They can conduct heat and electricity but not as well as metals.

Question 10

isotope

Answer 10

A variation of an element based on the number of neutrons in its nucleus. For example, carbon-14 has eight neutrons, while carbon-12 has only six. Carbon-12 in the most common isotope of carbon. Neutrons do not affect the number of electrons and protons (or the atomic number) in an element because neutrons do not have an electric charge.