Review 1st SW Elements and Compounds

What should you do as you enter the science classroom?

• Start Computer

  (Let it boot up

  while you get ready)

• Wait for instructions before touching any equipment or starting any activity.

  (Think Turn Talk)

• Enter Quietly/

  Find your seat

• Open your science journal and start with the date.

• (5 minute)

  Journal Entry

  (Short Constructed Response)

  Claim 1

  Proof 3

  Result 1

Answer explanation

The first step after spilling a chemical is to tell the teacher immediately. This ensures proper safety protocols are followed and minimizes risk, as the teacher can provide guidance on how to handle the situation safely.

A student wants to measure quantitative data for a science fair.

What do these tools measure?

• Thermometer for temperature

• 
• Stopwatch for time

• 
• Meter stick for length

• 
• Graduated cylinder for volume

• 
• Triple beam balance for mass

• 

Tags

NGSS.MS-PS1-2

NGSS.MS-PS3-1

In an experiment, the manipulated variable is the one that…

• Scientists measure

• Scientists keep the same

• Scientists change on purpose

• Happens naturally

Answer explanation

In an experiment, the manipulated variable is the one that scientists change on purpose to observe its effect on the dependent variable. This distinguishes it from variables that are measured or kept constant.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

Which is an example of inference?

• Saying a rock feels rough

• Measuring water temperature

• Explaining that the rock was once part of a mountain

• Reading a thermometer

Answer explanation

Inference involves drawing conclusions based on evidence. Explaining that the rock was once part of a mountain uses reasoning about its history, making it an inference, while the other options describe direct observations.

Which of the following are compounds?

Groups:

(a) Elements

,

(b) Compounds

• C₆H₁₂O₆

• O₂

• CO₂

• H₂O

• N₂

• Ne

• H₂

• NaCl

Tags

NGSS.MS-PS1-1

Water (H₂O) has 2 hydrogen atoms and 1 oxygen atom. What does the subscript “2” mean?

• Two molecules of water

• Two hydrogen atoms

• Two oxygen atoms

• Two compounds of water

Answer explanation

The subscript '2' in H₂O indicates that there are two hydrogen atoms in each molecule of water. It does not refer to the number of water molecules or oxygen atoms.

Tags

NGSS.MS-PS1-1

Match the terms that correctly analyze this molecule.

• 3

• Molecules

• 1

• Atoms of Hydrogen

• 6

• total Atoms

• 12

• Atoms of Oxygen

• 24

• Elements

Tags

NGSS.MS-PS1-1

Why are subscripts important in chemical formulas?

• They show the type of element

• They show the number of atoms of each element

• They separate molecules from compounds

• They show the mass of the atoms

Answer explanation

Subscripts in chemical formulas indicate the number of atoms of each element present in a molecule. This is crucial for understanding the composition and structure of compounds, making the correct choice "They show the number of atoms of each element."

Label the main categories of elements.

a

b

c

Nonmetals

Metalloids

Metals

Tags

NGSS.MS-PS1-1

Categorize the evidence of different changes:

Groups:

(a) Chemical change

,

(b) Physical change

• breaking

• precipitate

• change in mass

• evaporation

• temperature change

• Illumination

• Odor changes

• freezing

• melting

• folding

• Color change

• Gas formation

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5