The Scientific Process
In science, instead of saying an experiment “proved” something, what phrase should we use when the results agree with our hypothesis?
Results support the hypothesis.
What should you always wear to protect your eyes during a science lab?
Safety goggles.
What is the first step scientists take when beginning a scientific investigation?
They identify or define a problem to study.
In which state of matter are particles packed tightly together and only vibrate in place?
Solid.
What’s the difference between mass and weight?
Mass is the amount of matter in an object.
Weight is the pull of gravity on that mass.
What kind of property can be observed or measured without changing a substance’s identity?
A physical property.
What’s the main difference between a physical change and a chemical change?
A physical change changes the appearance, not the substance itself; a chemical change creates a new substance.
What are the two things every good hypothesis should include?
It should be testable and show a cause-and-effect relationship (If… then…).
Why is a hypothesis still valuable even if the data doesn’t support it?
Because it can lead to further investigation and help refine future experiments.
What should you do first if a chemical spills or an accident happens during a lab?
Tell the teacher immediately.
Why do scientists perform repeated trials in an experiment?
To make sure results are reliable and not caused by random chance.
How do particles move in a liquid compared to a solid?
They move more freely and can slide past each other.
What is the formula for density?
Density = Mass ÷ Volume (D = M/V)
Which physical property describes how easily heat or electricity moves through a material?
Conductivity.
Question: Which of these is a chemical change?
A) Boiling water
B) Breaking glass
C) Rusting iron
C) Rusting iron
During a lab, a student measures out 10 mL of vinegar and 5 g of baking soda. Which step of the scientific process is this?
Collecting and organizing data / performing the experiment.
What three things do scientists use to make sense of the evidence they collect during investigations?
Logical reasoning, imagination, and empirical evidence.
Why is it important to read the lab directions all the way through before starting an investigation?
So you understand each step, can gather all materials safely, and avoid mistakes or accidents.
What are the three main types of variables in an experiment, and what does each one do?
Independent variable: what is changed
Dependent variable: what is measured
Controlled variables: what stays the same
Describe how gas particles move and how much space is between them.
Gas particles move quickly in all directions and are far apart from one another.
A rock has a mass of 50 g and a volume of 10 cm³. What is its density?
5 g/cm³
Salt dissolves in water but sand does not. Which physical property explains this difference?
Solubility.
If 10 grams of ice melt into 10 grams of water, what does that show about mass during a physical change?
The Law of Conservation of Mass — mass is conserved; it doesn’t disappear or increase.
A student says, “The liquid turned yellow after I mixed it.” Is that an observation or an inference?
Observation — it’s something you can directly see.
(Inference would be explaining why it turned yellow.)
A geologist studies rock layers to explain Earth’s history, while a biologist studies fossils to explain evolution. What does this show about scientific explanations?
Different fields of science use different methods to develop explanations.
Why should you never eat, drink, or chew gum during a lab activity?
Because chemicals or bacteria could contaminate food and make you sick.
You’re testing how light affects plant growth. What is your independent and dependent variable?
Independent variable – amount of light; Dependent variable – plant growth.
When a solid turns directly into a gas, what is that process called?
Sublimation.
Why is density considered a physical property of a substance?
Because it can be measured or observed without changing the substance’s identity.
A magnet attracts an unknown metal. What can you conclude about that material?
It has magnetic properties—it contains iron, nickel, or cobalt.
How does temperature affect the rate of a chemical reaction?
Higher temperature makes particles move faster, causing more collisions and a faster reaction rate.
Which has more density — an object that sinks in water or one that floats?
The one that sinks — it’s more dense than water.
What is the main difference between science and pseudoscience?
Science relies on evidence, testing, and peer review; pseudoscience is based on beliefs or opinions without empirical support.
A student accidentally breaks a glass beaker but tries to clean it up quietly. What lab rule did they break, and what should they have done instead?
They broke the rule of reporting accidents immediately. They should have told the teacher and let them handle the cleanup safely.
After finishing an experiment, you notice one group’s data doesn’t fit the pattern. What’s the correct scientific response?
Recheck the data, look for errors, and repeat the investigation if needed instead of changing the results.
Explain how the particle motion and spacing changes as temperature increases.
As temperature increases, particles move faster and spread farther apart.
Two objects made of the same material have different sizes. How will their densities compare?
They’ll have the same density because density doesn’t depend on the amount of material.
Why do substances like water always boil at the same temperature under the same conditions, no matter how much you have?
Because melting and boiling points are characteristic properties that do not depend on the amount of the sample.
When you light a candle, what two main energy transformations happen?
Chemical energy changes to light and thermal (heat) energy.
A student burns a piece of paper and notices it turns to ash and releases gas. What law explains why the total mass before and after the reaction stays the same?
The Law of Conservation of Mass.