Atomic Structure and Periodic Table

Which of these statements describes a fact about an electron cloud?

• It is the most massive part of an atom.

• It is made up of electrons and neutrons.

• It is where an atom’s electrons are found.

• It is located in the center of an atom’s nucleus.

In the late 1800s, Ernest Rutherford set up an experiment to determine the qualities of the atom. He bombarded thin metal sheets with small particles. The result was that most of the particles went through the metal foil, mostly without changing course. What conclusion came from this experiment?

• Atoms are mostly empty space.

• Atoms have a positive charge.

• Atoms are composed of metal.

• Atoms are too small to see.

Why is the mass of an atom’s electrons not included in the atom’s mass number?

• The electrons move too fast to measure their mass.

• The electrons are much less massive than the rest of the atom.

• The electrons’ mass is represented in the atomic number.

• The electrons’ negative charge cancels out their masses.

Tags

NGSS.MS-PS1-5

An atom of lead has the atomic number 82 and a mass number of 207. How many neutrons does this atom of lead have?

• 82

• 125

• 207

• 289

Which of the following describes how elements are arranged in the periodic table?

• by decreasing atomic mass

• by increasing atomic number

• by chemical name

• by repeating atomic number

The periodic table has rows and columns that organize the elements by similarities. What is the name for a row in the periodic table?

• family

• group

• period

• series

Atoms of the element sulfur (S) have six valence electrons. Find sulfur on the periodic table above to answer the following question. Which elements also have only six valence electrons?

• elements within Period 3

• elements to the right of the zigzag line

• elements within Period 6

• elements within Group 16

Which element is in Period 4, Group 6?

• Ti

• Cr

• Hf

• W

In the periodic table above, find the element with the average atomic mass of 132.9. Which of the following is the chemical symbol for this element?

• Cs

• Ba

• La

• Hf