NGS CH09 - Section 3: The Periodic Table

Who created the first periodic table of elements?

• Marie Curie

• Albert Einstein

• Henry G. J. Moseley

• Dmitri Mendeleev

Answer explanation

Dmitri Mendeleev is credited with creating the first periodic table of elements in 1869. He organized elements by atomic mass and predicted the properties of undiscovered elements, laying the foundation for modern chemistry.

How did Dmitri Mendeleev initially arrange the elements in the periodic table?

• By atomic number

• By color

• By increasing atomic mass

• Alphabetically

Answer explanation

Dmitri Mendeleev initially arranged the elements by increasing atomic mass. This method allowed him to identify patterns and predict the properties of undiscovered elements, leading to the development of the periodic table.

Who rearranged the periodic table by atomic number in 1913?

• Niels Bohr

• Dmitri Mendeleev

• Isaac Newton

• Henry G. J. Moseley

Answer explanation

Henry G. J. Moseley rearranged the periodic table by atomic number in 1913, establishing that elements should be ordered by their atomic number rather than atomic mass, which improved the organization of the table.

What is the modern periodic table organized by?

• Atomic mass

• Color

• Alphabetical order

• Atomic number

Answer explanation

The modern periodic table is organized by atomic number, which is the number of protons in an atom's nucleus. This arrangement reflects the periodic law, where elements with similar properties appear at regular intervals.

What are the vertical columns in the periodic table called?

• Levels

• Rows

• Groups

• Periods

Answer explanation

The vertical columns in the periodic table are called 'Groups'. Each group contains elements that share similar chemical properties, distinguishing them from the horizontal rows, known as 'Periods'.

How many groups are there in the periodic table?

• 20

• 12

• 18

• 7

Answer explanation

The periodic table has 18 groups, which are the vertical columns that categorize elements based on similar properties. Each group contains elements with similar chemical behavior, making 18 the correct answer.

What do elements in the same group have in common?

• Same number of protons

• Same number of electrons in their outer energy level

• Same atomic mass

• Same color

Answer explanation

Elements in the same group of the periodic table share similar chemical properties due to having the same number of electrons in their outer energy level, which influences their reactivity and bonding behavior.

What are the horizontal rows in the periodic table called?

• Columns

• Periods

• Levels

• Groups

Answer explanation

The horizontal rows in the periodic table are called periods. Each period represents a different energy level of electrons in the atoms of the elements in that row.

How many periods are there in the periodic table?

• 5

• 6

• 8

• 7

Answer explanation

The periodic table consists of 7 periods, which are the horizontal rows of elements. Each period corresponds to the number of electron shells in the atoms of the elements in that row.

What happens at the end of each row in the periodic table?

• The elements become gases

• The atomic mass doubles

• An outer energy level is filled

• A new group starts

Answer explanation

At the end of each row in the periodic table, an outer energy level is filled with electrons. This filling corresponds to the completion of the electron configuration for the elements in that row.