Scientific Method
What is the difference between an independent and dependent variable?
What is: the independent variable is what you change, and the dependent variable is what you measure?
Name the three main states of matter.
What are: solid, liquid, and gas?
What is an atom?
What is: the smallest unit of matter that makes up an element?
What does a row (period) on the periodic table represent?
What is: a horizontal row that shows the number of electron shells?
What is the difference between a physical and chemical change?
Physical: no new substance. Chemical: new substance formed.
What is a control group in an experiment?
What is: the group that does not receive the independent variable and is used for comparison?
What is the difference between a solid and a liquid?
What is: a solid has a fixed shape, while a liquid takes the shape of its container?
How do you calculate the number of neutrons in an atom?
What is: subtract the atomic number from the atomic mass?
What does a column (group/family) on the periodic table indicate?
What is: elements with similar properties and the same number of valence electron
You observe that salt dissolves in water, but the salt is still present. What type of property is this — physical or chemical?
Physical property — dissolving is a physical change, and the salt retains its identity.
What is a constant in a scientific experiment?
What is: a variable that stays the same throughout the experiment?
What phase change occurs when a gas turns into a liquid?
What is: condensation?
How many protons, electrons, and neutrons are in an atom of Carbon-12?
What are: 6 protons, 6 electrons, and 6 neutrons?
What is the atomic number and what does it tell us?
What is: the number of protons in an atom?
A piece of paper burns and turns into ash and smoke. What kind of change is this, and what does it show?
Chemical change — because a new substance is formed and the change cannot be reversed easily.
identify the independent and dependent variables: A student tests how sunlight affects plant growth.
What is: the independent variable is the amount of sunlight, and the dependent variable is the plant growth?
Compare and contrast physical and chemical changes.
What is: a physical change does not form a new substance, but a chemical change does?
Define atomic number, atomic mass, and atomic symbol.
What is: atomic number = number of protons, atomic mass = protons + neutrons, atomic symbol = abbreviation for the element?
How are elements in the same family similar?
What is: they have similar chemical properties and the same number of outer electrons?
What are signs that a chemical change has occurred?
What is: color change, temperature change, formation of a gas (bubbles), or a new substance formed?
Why is it important to only change one variable at a time in an experiment?
What is: to make sure the results are only affected by the one variable being tested?
Describe what happens to particle motion during melting and freezing.
What is: during melting, particles move faster and spread apart; during freezing, they slow down and come closer?
neutral atom has 15 protons. How many electrons and neutrons does it have if the atomic mass is 31?
What are: 15 electrons and 16 neutrons
Why is the periodic table called “periodic”? What trends can be observed?
What is: it shows repeating patterns of properties, such as increasing atomic number and similar reactivity in groups?
What is the difference between a physical and chemical property?
physical property can be observed without changing the identity of the substance (e.g., boiling point), while a chemical property describes the ability to change into a different substance (e.g., rusting)?