Chapter 2: Science, Matter, Energy, and Systems

Science

A field of study focused on discovering how nature works and using knowledge to describe what will likely happen in nature

• Observations

• Measurements

• Experimentation

Scientific Method

1. Identify a problem

2. Gather relevant data

3. Propose a hypothesis to explain the data

4. Perform an experiment, collect data, and analyze data to test the hypothesis

5. Modify the hypothesis as needed

Hypothesis

An educated guess

• Must be testable

• Can be proven/supported or disproven/refuted/not supported

• It can’t be right or wrong

Designing experiments

• Needs to be controlled experiment

• Independent variable - the factor that is changed

• Dependent variable - factor that is measured as it responds

• Control group - a group that has nothing done to it

Analyzing data

• Quantitative data - counted measure, includes numbers

• Qualitative data - not counted, descriptions

Models

• Created when you can’t do an experiment

• A physical or mathematical representation

Theory

A well-tested and widely accepted hypothesis

Law

A rule that describes an action/set of actions in the universe

• Never proven or disproven

• Doesn’t explain how or why something happens

Peer Review

When scientists publish details of methods they used, results of their experiment, and the reasoning behind their hypotheses for other scientists in the same field to evaluate 

• Critical for scientific advancements

• Thick critically

• Shows difference between reliable, unreliable, and tentative science

• Tentative science - preliminary scientific results; not adequate testing

Atom

The smallest unit of an element

Atomic Number

Number of protons in the nucleus of an atom

Cells

Smallest living unit of an organism

Chemical change

Interaction between chemical, the chemical composition is changed

Chemical formula

The number of atoms or ions in the structure of a compound

Compounds

Combination of atoms of two or more elements held together by chemical bonds

Electrons

Tiny particle moving around the outside of the nucleus

Elements

Chemical who have different atoms that serve as the building blocks of matter

Ion

Atom or group of atoms with one or more positive/negative electrical charge

Isotopes

Two or more forms of an element; same number of protons but different mass number and different number of neutrons

Law of Conservation of Matter

Matter is not created or destroyed; it is changed from one form to another form

Mass number

Sum of the number neutrons and protons

Matter

Anything that has mass

Molecule

Combination of two or more atoms of the same element or different chemical elements held by chemical bonds

Neutrons

No electrical charge; located within the nucleus

pH

Indicates acidity, anything below 7 and if something is basic, anything above 7

Physical change

A process that alters the physical properties of an element/compound without changing its chemical composition

Proton

A positively charged particle within the nucleus

System

Set of components that interact in a regular way

• Inputs, flows, outputs of matter, energy and information

• Feedback can affect behavior

Feedback

Any processes that increase or decrease a change to a system

• Positive feedback - causes the system to change further in the same direction

• Negative feedback - causes the system to change in opposite directions

• Most systems in nature use negative feedback to enhance long-term stability

Ecological tipping point

Natural system stuck in positive feedback loop

• It will eventually reach the tipping point

• Suffer severe degradation or collapse