What’s It Made Of?
Is oxygen gas (O₂) an element, a compound, or a mixture? Give one quick reason.
Element; it’s made of only oxygen atoms.
Sweet tea (sugar completely dissolved): homogeneous or heterogeneous mixture?
Homogeneous (a solution).
Is sodium (Na) a metal, nonmetal, or metalloid?
Metal (an alkali metal)
This is the variable the scientist changes on purpose in an experiment.
Independent variable
What should you wear to protect your eyes in the lab?
Goggles
Are water (H₂O) and table salt (NaCl) elements or compounds? How do you know?
Compounds; each has two different elements chemically bonded.
Trail mix: homogeneous or heterogeneous? Give one property that proves it.
Heterogeneous; you can see and pick out different parts.
Elements in the same group (column) often share what in common?
Similar properties (like similar reactivity)
This is the variable the scientist measures or observes in an experiment.
Dependent variable
What’s the safe way to smell a chemical?
Waft; gently fan vapors toward your nose (don’t sniff directly).
Which are compounds: CO or CO₂? Explain your thinking in one sentence.
Both are compounds; each has carbon bonded with oxygen (just in different amounts).
What’s one simple way to separate sand from salt water?
Filter out the sand, then evaporate the water to get the salt.
How many different kinds of atoms are in CaCO₃? Name them.
Three; calcium (Ca), carbon (C), oxygen (O).
In an experiment testing if fertilizer helps plants grow, the plants that get no fertilizer represent this part of the experiment.
Control group?
Glass breaks at your table. What should you do?
Tell the teacher, keep others away, and let the teacher use proper cleanup tools.
Copper and sulfur chemically bond in a 1:1 ratio. Write the simplest formula and say what type of substance it is.
CuS, a compound.
**Daily Double**
Two clear liquids look the same. How could you tell if one is a solution and the other is a pure compound? Name one quick test.
Boiling point test ; or evaporation
Which side of the periodic table has most nonmetals?
The right side (above/right of the staircase, including halogens and noble gases).
These are the things that must stay the same in an experiment to keep it fair.
Constants
You spill acid on your hand. What’s your first move?
Rinse with lots of water immediately and tell the teacher.
A clear liquid always breaks into hydrogen and oxygen gas when tested. Element, compound, or mixture? How do you know?
Compound; it has a fixed composition that can be broken into simpler substances (elements).
A white powder in water won’t dissolve; the particles sink after stirring. What kind of mixture is this, and how could you separate it?
Heterogeneous. Filtration would separate it.
**Daily Double**
For Al₂O₃, name each element and say if it’s a metal or nonmetal.
Aluminum (metal) and oxygen (nonmetal)
A student tests whether listening to music improves test scores. She gives one group of students music, another group no music, and makes sure they all take the same test in the same classroom.
Identify the independent variable, dependent variable, and a constant.
Independent variable = music vs. no music
Dependent variable = test scores
Constant = same test, same classroom.
A classmate wants to test if sugar burns by holding it over a flame with no plan. Why is this unsafe?
No hazard plan/PPE; risk of burns and smoke.