Basics of the Periodic Table: Introduction and Key Concepts

Recall: What is an element according to the lesson’s vocabulary? Choose the best definition.

• A mixture of different types of atoms

• A pure substance made of only one type of atom

• A compound formed by two or more elements

• Any substance with a chemical symbol

Recall: What does the chemical symbol represent?

• The atomic mass of an element

• A one or two letter symbol that represents the element

• The number of neutrons in the element

• A picture of the element’s discovery

Skill/Concept: In 1869, how did Dmitri Mendeleev organize the known elements, and what notable action did he take in his table?

• He arranged them by atomic number and filled every space

• He arranged them by atomic mass and left blanks for undiscovered elements

• He grouped them by color and removed metals

• He listed them alphabetically and ignored unknowns

Skill/Concept: What does the term periodic mean in science contexts like the periodic table?

• Randomly occurring at different intervals

• Occurring once and never repeating

• Means to be repeated in a pattern

• Changing unpredictably over time

Strategic Thinking: Early versions of the periodic table arranged elements by increasing atomic mass. Later, scientists realized this did not always increase what number, leading to a change in how the table is organized. What is the modern organizing number and why?

• Atomic mass, because it always increases with more protons

• Atomic number, because it counts the number of protons in the nucleus

• Density, because heavier elements sink

• Valence electrons, because they determine bonding in all cases

Match the concept to its description based on the lesson.

• One- or two-letter representation of an element

• Chemical symbol

• A pure substance made of only one type of atom

• Atomic number

• The number of protons in an atom

• Atomic mass

• A measure related to the mass of an atom (e.g., fluorine shown as 18.998)

• Element

On the periodic table, what is a period?

• A row that goes across the table; there are 7 periods

• A column that goes down the table; there are 18 periods

• A diagonal line separating metals from nonmetals

• A group of elements with the same mass number

Which statement best defines a group on the periodic table?

• A row across the table containing 7 elements

• A column down the table whose elements share many properties; there are 18 groups

• A box that shows the element’s name and symbol

• A set of elements arranged by increasing mass

Match each element type with one key property.

• Good conductors of heat and electricity

• Metalloids

• Poor conductors; tend to be dull

• Metals

• Can conduct electricity, but not as well as metals

• Nonmetals

Which set lists properties typical of metals at room temperature?

• Solid (except mercury), malleable and ductile, metallic luster, good conductors

• Usually gases, brittle when solid, dull appearance, poor conductors

• Solid, colorful, easily shattered, insulators

• Liquid, non-ductile, no luster, poor heat conductors