Question

8 true or false 1 point
ionization energy can be negative.
true
false

9 multiple choice 1 point
the concept of the atomic number was originated by...
moseley
bohr
meyer
mendeleev

10 multiple choice 1 point
what is one characteristic that distinguishes metalloids from metals?
metalloids struggle to conduct heat.
metalloids are generally liquids.
metalloids cannot be shiny
metalloids cannot conduct electricity

Explanation:

Question 8 (True or False)

Step1: Recall Ionization Energy Definition

Ionization energy is the energy required to remove an electron from an atom (or ion) in the gaseous state. By definition, energy input (positive value) is needed to overcome the attractive force between the nucleus and the electron. So it cannot be negative.

Step2: Evaluate the Statement

The statement "Ionization energy can be negative" is false because ionization energy is the energy required (positive) to remove an electron.

Henry Moseley originated the concept of atomic number (the number of protons in an atom's nucleus). Bohr developed the Bohr model of the atom, Meyer contributed to the periodic table's development (along with Mendeleev, who is known for the periodic table's organization by atomic mass initially), and Mendeleev is known for the periodic table based on atomic mass. So the correct option is Moseley.

• Metals are good conductors of heat; metalloids have intermediate heat conductivity (so "Metalloids struggle to conduct heat" is correct).
• Metalloids are solids (not generally liquids), so the second option is wrong.
• Metalloids can be shiny (e.g., silicon has a metallic luster), so the third option is wrong.
• Metalloids are semiconductors (can conduct electricity under certain conditions), so the fourth option is wrong.

Answer:

False

Question 9 (Multiple Choice)