What I Should Know Science
Perform the following conversion. 123 cm to m
1.23 m
How many hydrogen (H) atoms are in five molecules of ammonia (NH3)?
15 The numbers of each atom are indicated by subscripts within the chemical formula, so the number five would be multiplied by the subscript. Three atoms of hydrogen times five equals fifteen total atoms of hydrogen.
Calculate the area of a floor that is 1.5 × 103 m long and 2.2 × 102 m wide.
3.3 × 105 m*2 330,000
How many nitrogen (N) atoms are in five molecules of ammonia (NH3)?
5 The numbers of each atom are indicated by subscripts within the chemical formula, so the number five would be multiplied by the subscript. Since there is only one atom of nitrogen, no subscript is used. Five times one equals five atoms of nitrogen.
Describe how the terms reactant, product, and chemical change relate.
A chemical change occurs when the identity of one substance transforms into another substance or substances. A reactant is the starting substance of a chemical reaction that gets changed. A product is a substance formed by changing a reactant or reactants in a chemical reaction.
What is a compound? Provide three examples.
A compound is the smallest unit of a pure substance that is formed when atoms of different elements come together. Examples are carbon dioxide (CO2), water (H2O), and salt (NaCl).
Which best explains what happens when scientists submit their work to a scientific journal for peer review?
A group of scientists judges the soundness of the experiments that are submitted for publication.
What are derived units?
Derived units are produced using one or more units in a combination.
Why is detailed and accurate data important?
Detailed and accurate data makes it easier for scientists to understand and communicate the results of their experiments to their peers and the public.
What are some example reactions that represent the four indicators of a chemical change?
color change—copper oxidizing and turning from red-orange to green gas formation—hydrogen peroxide (H2O2) reacting with catalase in blood and producing bubbles of oxygen solid formation—sodium chloride (NaCl) mixing with silver nitrate (AgNO3) to form a precipitate (AgCl) change in energy—mixing concentrated acids with water in the correct proportions so liquid boils
Experimental factors that cannot be changed are called ______.
constants
A variable that a scientist decides to hold constant is called a _______ variable.
controlled
What are some characteristics of scientific thinking?
curious, open-minded, skeptical, unafraid
The dependent variable ______ the independent variable.
depends on
Identify examples of direct and indirect observations.
direct observations—odor of a chemical reaction, color of a substance, texture of a material, and temperature of a liquid indirect observations—the number of electrons in an element, the shape and size of nebula, and the date of fossils
Scientists revise their hypotheses and conduct further investigation after they ______
draw conclusions
Give an example of a molecule.
examples include glucose (C6H12O6), silica (SiO2), and oxygen gas (O2)
Predictions are not _______ statements, so it does not matter if they turn out to be ________.
factual; false
How is the periodic table organized?
in rows and columns
How can information about physical properties and changes be used in science and everyday life?
in science—to create safer and more effective tools, devices, and buildings in everyday life—to help with all kinds of tasks, such as cooking
In an experiment, the factors that scientists change or manipulate are _[blank]_ variables. _[blank]_ variables are the factors that scientists measure and record, and _[blank]_ variables are the factors that scientists intentionally keep constant.
independent; Dependent;controlled
A variable that a scientist decides to manipulate on purpose is called a(n) ______ variable, while a variable that is observed or measured is a(n) _________ variable.
independent; dependent
A statement that summarizes an observed pattern in nature without providing explanation is a scientific _____.
law
Identify the steps of the scientific method.
make an observation, form a hypothesis, conduct an experiment, analyze the results and draw conclusions, and communicate results
Human curiosity has led to improvements in technology, which has increased scientists' ability to _[blank]_.
make observations
What two physical properties depend on the sample size of a substance? Give examples for each.
mass—coins of the exact same size made with different metals have a different mass volume—the volume of water vapor is over 1,600 times larger than the volume of liquid water with the same mass
Upon what two things should a hypothesis be based?
observation and research
What is the difference between organic and inorganic compounds?
Organic compounds contain carbon and other elements and make up living organisms. Most inorganic compounds do not contain carbon and play a supporting role in living organisms.
Explain what outliers are. How do scientists deal with them, and how does this affect graphs?
Outliers are data values that are very different than the majority of the other values. Scientists drop data values that are outliers, which makes the patterns and trends on graphs easier to see.
What is oxidation? Provide an example.
Oxidation is the process in which oxygen reacts with substances. An example of this occurs when iron rusts. When this happens, iron reacts with oxygen in the air and forms iron oxide (Fe2O3).
How are plasmas similar to gases, and how are they different?
Plasmas, like gases, have a volume and shape that are varied instead of fixed. However, plasmas are made of charged particles that conduct electricity, while gases are not.
Why do scientists use tables and graphs?
Tables and graphs help scientists organize and display data as well as organize patterns.
Why is technology important for making observations?
Technology has increased scientists' ability to make observations beyond their own senses, allowing them to discover more about the world.
Review the list of facts. Identify which molecule or compound matches each fact listed. Write the name of each substance with a dash followed by the appropriate fact. makes up 21% of Earth's air a simple sugar used to generate energy in living organisms a main component of sand covers about 71% of Earth's surface produces a "fog" effect when it changes from solid to liquid
oxygen gas (O2)—makes up 21% of Earth's air glucose (C6H12O6)—a simple sugar used to generate energy in living organisms silica (SiO2)—a main component of sand water (H2O)—covers about 71% of Earth's surface carbon dioxide (CO2)—produces a "fog" effect when it changes from solid to liquid
Why can gases be compressed easily?
The large amount of space between gas particles makes it easy to compress gases.
Study the conclusion. Fertilizer makes tomato plants produce bigger fruit. Which statement best supports the conclusion? (Select all that apply.)
Tomato plants that receive fertilizer produce fruit that is bigger than tomato plants that do not receive fertilizer. Tomato plants that receive no fertilizer produce fruit that is smaller than tomato plants that do receive fertilizer.
Examine the statement. If a scientist observes ice cream melting into a creamy puddle, the scientist is observing a physical change. Determine whether the statement is true or false. If false, explain why it is false.
True
Batteries usually have a volt rating. The unit of a volt is Joule/Coulomb. Is a volt a derived or base unit?
a derived unit
What is a molecule?
a pure substance that is formed when two or more atoms of the same type join
List the information that can be found for each element in the periodic table.
atomic number, element symbol, element name, and average atomic mass
Which of the scenarios represents a chemical change?
autumn leaves changing color
How can scientists control the flammability of a substance?
by modifying the amount of pressure, amount of oxygen, and temperature surrounding the substance
The following statement is false. An atom can be broken into smaller atoms. Reword the statement so it is true
cannot*
What are the symbols for carbon, oxygen, helium, and hydrogen? Hint: Look at your periodic table.
carbon—C oxygen—O helium—He hydrogen—H
What are the four indicators that a chemical reaction has occurred?
change in color, formation of a gas, formation of a solid (precipitate), and change in energy
Identify the most common graph types, and explain what each is used for.
circle graphs—illustrate how a part relates to a whole bar graphs—compare quantities among groups and show large changes over time histograms—show the distribution and frequency for a set of data values line graphs—display small changes and patterns in data as well as compare two sets of data scatter plots—help identify a possible relationship between two groups of numerical data
While _[blank]_ science deals with knowledge discovery, _[blank]_ science deals with knowledge use.
pure; applied
Compare and contrast qualitative and quantitative data.
qualitative data—deals with characteristics or qualities expressed in words; displayed in circle and bar graphs quantitative data—deals with quantities expressed in numbers; displayed with circle, bar, and line graphs as well as histograms and scatterplots
What are the characteristics of quantitative and qualitative data?
quantitative data—numerical; produced through measuring or counting objects qualitative—descriptive; includes characteristics and properties of objects
Data made of numbers obtained from counting or measuring objects is _[blank]_, while data made of descriptions obtained from observing properties and characteristics of objects is _[blank]_.
quantitative; qualitative
A substance's ability to change into another substance is the substance's _______.
reactivity
What can cause an accepted scientific theory, or even a scientific law, to change?
repeated experimental evidence that does not support the theory or law
A scientific _[blank]_ is an explanation for observable facts that is supported by experimental evidence. A scientific _[blank]_ is a statement that summarizes a pattern observed in nature. Which answer choice presents the correct words to complete the sentence?
theory; law
Why do experimenters typically run multiple trials for an experimental group?
to prevent error
Examine the following statement. The atoms of different elements have different masses. Determine whether the statement is true or false. If false, explain why it is false.
true
Examine the false statement. Conclusions can be reached before an analysis of the experimental data. Reword the statement so it is true.
Conclusions can be reached AFTER an analysis of the experimental data.
Examine the false statement. A substance's density is determined by dividing its matter by its volume. Reword the statement so it is true.
A substance's density is determined by dividing its mass by its volume.
What does dividing the parts of an atom do to its identity?
An atom that is broken down into its parts (protons, neutrons, and electrons) is no longer recognizable. Only when the protons, neutrons, and electrons are united in the appropriate structure and form can they be identified as an atom.
Examine the false statement. An object's mass and volume contribute to its kinetic energy, so if one of those factors increases, then the object's kinetic energy will increase as well. Reword the statement so that it is true.
An object's mass and VELOCITY contribute to its kinetic energy, so if one of those factors increases, then the object's kinetic energy will increase as well.
Study the image. Then answer the question about it. What wording should be used for A and B to complete the diagram? IMAGE: -> independent variable -> \ /dependent variable->
A—changes because of B—influences
What items are necessary to conduct a well-designed investigation? Select all that apply.
Experimental constants An independent and dependent variable Experimental and a control group
Examine the following statement A hypothesis is a statement of fact. Determine whether the statement is true or false. If the statement is false, explain why it is false.
False. A hypothesis is a statement that provides a possible solution or answer to a problem or question that can be tested.
Examine the following statement. All individual atoms have the same size. Determine whether the statement is true or false. If false, explain why it is false.
False. Different kinds of individual atoms have a different mass and volume.
Examine the statement. Particles within matter have no kinetic energy because they are too small. Determine if the statement is true or false. If false, explain why it is false.
False. Matter's particles are in constant motion, which means they have kinetic energy.
If liquids cannot burn, what makes them flammable? Give an example of a flammable liquid.
Flammable liquids are volatile, or form gases easily. The gases of flammable liquids are what burn, not the liquids themselves. Gasoline is an example of a flammable liquid.
Explain how frosted shredded wheat cereal models a compound.
Frosted shredded wheat cereal contains two different parts joined together: bale fiber and frosting. Compounds are made of a least two different elements. The different parts of the cereal represent different elements
State the location of the independent and dependent variables on a graph.
Independent - x-axis Dependent - y-axis
Why is peer review important to science?
It strengthens the reliability of scientific information and helps scientific ideas progress in an orderly fashion.
Distinguish between pure and applied science.
Pure science deals with scientific discovery, while applied science deals with knowledge use.
[blank]_ are the materials that change in a chemical reaction, while _[blank]_ are the substances formed by changes in a chemical reaction.
Reactants; products
How do the methods of scientists lead to knowledge?
Researchers in science make observations, design experiments, and collect data. Then they review and use their findings to develop a reasonable explanation for what happened in their experiments. This allows scientists to build knowledge.
Which of the following can happen when scientists analyze their experimental data and draw conclusions? Select all that apply.
Scientists confirm their hypotheses. Scientists reject their hypotheses.
Describe why the kinetic theory of matter is important, and identify its basic ideas
Scientists use the kinetic theory of matter to study how energy affects the motion of particles within matter. The kinetic theory of matter has the following basic ideas: matter is made of small particles, there is empty space between each of the particles, and all of the particles are in constant motion or vibration.
What is the SI system? What are its benefits?
The SI system is a standard system of measurement used in the scientific community that is based upon powers of 10. Its benefits are that it is easy to convert units and it is internationally used, which provides scientists with a "universal language" for comparing experimental results.
What is the difference between a control group and an experimental group?
The experimental group receives the variable that is tested in different amounts, while the control group does not receive or receives a constant amount of the variable that is changed or manipulated.
Examine the false statement. Liquids are flammable. Select the reworded sentences that make the statement true. Select all that apply.
The gases of liquids are flammable. Liquids are not flammable.
Read the scenario. A little girl playing on the beach scoops one handful of sand into a bucket. Then, while in the same spot, she scoops two handfuls of sand into a second bucket. Based on the scenario, is the first bucket of sand's temperature and thermal energy the same as the second bucket of sand's? If not, why?
The two buckets of sand have the same temperature, but not the same amount of thermal energy. Since the sand came from the same spot, it most likely has the same average kinetic energy. However, the second bucket has more moving sand particles in it, so it has more total kinetic energy (thermal energy)
How do liquids differ from gases when they are transferred from one container to a container of a different size?
The volume of a liquid stays the same when it is transferred from one container to a container of a different size, but the volume of a gas expands or contracts.
What are some reasons a scientist's work could be rejected for publication?
The work could contain error or bias, or be based on poor experimental design.
You are going to conduct an experiment that examines how fertilizer affects plant growth. What are some controlled variables that you could include in your experiment?
There are many factors that could affect plant growth that would need to be controlled. The following are a few examples: amount of light, amount of water, soil type, amount of soil, temperature, plant type, humidity level, time of fertilizer application, and time of watering.
Why are the substances O2, H2, and S8 considered elements?
They contain one type of atom.
Scientific journals are peer reviewed. What does this mean?
They have a group of scientists that judges the soundness of experiments that are submitted for publication.
When the thermal energy of a substance or an object increases or decreases, what does this indicate?
When the thermal energy increases, the substance or object has absorbed energy from its surroundings. When the thermal energy decreases, the substance or object has released energy to its surroundings.
Yellow sulfur has a formula of S8. Is yellow sulfur a compound? Explain your reasoning.
Yellow sulfur is not a compound because it does not contain different elements. It consists of eight atoms of just sulfur.
physical change
a change that does not alter the identity of a substance
What is a controlled experiment?
a study with set conditions that involves testing only one variable at a time
Which phase changes require an absorption of energy, and which require a release of energy?
absorption of energy—melting, evaporation, sublimation release of energy—freezing, condensation, deposition
What is matter?
any physical substance that takes up space and has mass
Norman thinks that the brain function of students suffers when they receive less sleep. He predicts that students who get less sleep before an exam will receive lower test grades. To investigate his idea, he tests two groups of chemistry students. Group 1 receives four hours of sleep, while Group 2 receives the recommended eight hours of sleep the night before the exam. Both groups consume the same foods before testing and take the same exam in the same room. The room has a constant temperature and level of light for all students. What is the independent variable in Norman's investigation?
the amount of sleep students receive before their test
What is scientific knowledge made of?
the ideas that scientists understand and can reasonably explain
What stays the same in a physical change?
the identity of the substance, compound, or element
What do the subscripts in C6H12O6mean?
the molecule has 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms bonded together
What is transformed in a physical change?
the physical state and appearance of a substance
Norman thinks that the brain function of students suffers when they receive less sleep. He predicts that students who get less sleep before an exam will receive lower test grades. To investigate his idea, he tests two groups of chemistry students. Group 1 receives four hours of sleep, while Group 2 receives the recommended eight hours of sleep the night before the exam. Both groups consume the same foods before testing and take the same exam in the same room. The room has a constant temperature and level of light for all students. What is the dependent variable in Norman's investigation?
the range of grades students receive on their exam
What do scientists use to make observations?
their five senses: sight, hearing, taste, smell, and touch
An explanation for observable facts that is supported by experimental evidence is called a scientific _______
theory
