8th Grade Category 1

(8.5A) An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?

• +25
• +30
• -25
• -30

(8.5A) Which of these best describes one of the subatomic particles that could be found at location X in the model of an atom shown above?

• It has mass but no charge.
• It has no mass and a positive charge.
• It has a large mass and a negative charge.
• It has no mass and an equal number of positive and negative charges.

(8.5B) An atom of which element is represented by this model?

• Boron (B)
• Carbon (C)
• Neon (Ne)
• Sodium (Na)

(8.5B) When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with? 

• The total number of neutrons in the unknown element.
• The total number of particles in the nucleus of the unknown element
• The number of protons in the nucleus of the unknown element
• The number of valence electrons in the unknown element.

(8.5C) The periodic table is organized into groups and periods of elements. The characteristics of a certain group of elements are listed below.
-is shiny
-is solid at room temperature
-has atoms with two valence electrons
Which of these elements is in this group? 

• Lithium
• Strontium
• Aluminum
• Silicon

(8.5C) A student is studying the ways different elements are similar to one another. Diagrams of atoms from four different elements are shown below.
Which two atoms are of elements in the same group in the periodic table?

• Atom 1 and Atom 2
• Atom 1 and Atom 4
• Atom 2 and Atom 3
• Atom 3 and Atom 4

(8.5C) A researcher wants to experiment with an element that reacts like phosphorous (P) but has a greater atomic mass. Which element should the researcher select for the experiment?

• Nitrogen (N)
• Sulfur (S)
• Arsenic (As)
• Silicon (Si)

(8.5D) The chemical formula for sodium sulfate is Na₂SO₄. How many sulfur atoms are in the formula for sodium sulfate?

• 1
• 2
• 6
• 7

(8.5D) Serotonin is a chemical substance that acts as a neurotransmitter. It helps relay messages in the human brain. The formula for one molecule of serotonin is shown below.
C₁₀H₁₂N₂O
How may atoms in all are in a molecule of serotonin? 

• 10
• 25
• 24
• 100

(8.5D) Which information could a student determine from only the chemical formula of a protein? 

• The color of the protein
• The number of molecules in each sequence that makes up a protein
• The physical arrangement of atoms in the structure of the protein
• The number of atoms of each element in the protein