Unit 1: Properties of Matter 8.6

Examine the four models shown. Which model represents an element?

• A

• B

• C

• D

Tags

NGSS.MS-PS1-1

Sarah created a model of a compound as shown. She is unsure whether her model accurately represents a compound. Which statement correctly describes the molecules in her model?

• Her model represents an element.

• Her model represents a compound.

• Her model represents a homogeneous mixture.

• Her model represents a heterogeneous mixture.

Tags

NGSS.MS-PS1-1

John observes and analyzes two models of different types of mixtures as shown. Which statement explains which model represents a homogeneous mixture?

• Model A, because the particles are uniformly mixed.

• Model B, because the particles are not uniformly mixed.

• Model A, because the particles are organized by color.

• Model B, because the particles are tightly packed together.

There is a direct relationship between structure and function of substances on the atomic scale. A compound is made up of more than one (a)   , arranged in a way that determines the function of the substance. Carbon dioxide, or CO₂, is a(n) ​ (b)   . One molecule of CO₂ is made of ​ (c)   types of atom(s). Carbon monoxide, or CO, is a(n) ​ (d)   and is made of ​ (e)   types of atom(s). Because carbon dioxide and carbon monoxide have different structures , carbon monoxide is a toxic gas, and carbon dioxide is a common gas that is dissolved in carbonated drinks.​

• element
• compound
• two
• three
• atoms

Tags

NGSS.MS-PS1-1

What is anything that has mass and takes up space?

• matter
• substance
• chemistry
• property

On a summer morning, rounded drops of water can be seen on the leaves of trees and grass. Which property of water causes it to form these rounded drops?

• cohesion

• adhesion

• condensation

• surface tension

How can the properties of water be described?

In the early morning, dew drops can be seen clinging to the strands of spider webs, appearing like strings of glass beads. The water drops are held to the web by ​ (a)   . This is because of the ​ (b)   between the water molecules and the molecules in the web. The drops are round because of the ​ (c)   of ​attraction between water molecules, called ​ (d)   . This is what causes a high ​ (e)   on the outside of the drop.

• repulstion
• capillary action
• adhesion
• attraction
• forces
• cohesion
• surface tension

Two students carry out an experiment using these steps: • Carefully place a needle on the surface of a bowl of pure water. • Add a few drops of liquid soap to the water. • Observe that adding soap causes the needle to sink to the bottom. Which conclusion can the students draw from the results of their experiment?

• The soap increased the weight of the needle.

• The soap reduced the surface tension of the water.

• The soap molecules repelled the needle molecules.

• The soap increased the forces between water molecules.

Water has several unusual properties that help describe phenomena of water behavior. Which phrases describe each property of water?

• adhesion

• Water forms a concave meniscus, or curved part, when in a graduated cylinder.

• surface tension

• Water molecules form rounded beads.

• cohesion

• Many objects can float in water, even if they are more dense than water.

Liquid water can be observed behaving in different ways. How can each observed behavior be classified by adhesion, cohesion, or both?

Groups:

(a) Adhesion

,

(b) Cohesion

,

(c) Both Adhesion and Cohesion

• A dish in a drying rack remains wet for an hour.

• A water strider insect walks across the surface of a pond.

• Dew drops cling to the bottom of a leaf.

• The small drops that cling to a bathroom mirror are dome shaped.

• A raindrop takes a rounded shape as it falls.