Unit 1 Textbook/Slide definitions

Scientific method, Molecules of life, Atoms, Chemical bonds, Water, Carbon, Organic Molecules

Observation

- The act of viewing the world around us

- Using your senses to notice things

Experimentation

To test the hypothesis

Scientific literature

Published information about experiments/observations that others have done

EX: Articles, papers

Hypothesis

A statement to test

(What you think will happen in an experiment/study)

Hypotheses

More than one hypothesis

(plural form of hypothesis)

Prediction

The expected outcomes of an experiment

Controlled experiment

A test where only one thing is changed to see its effect, while everything else stays the same

Variable

• Something that can change or be changed in an experiment

Test (experimental) group

• The experimental group thats is exposed to a variable in the experiment

• The group in an experiment that gets the change or treatment being tested.

Control group

• The group that is not exposed to the variable in an experiment

• The group in an experiment that doesn’t get the treatment—used for comparison.

Elements

• Basic/pure substances (can’t be broken down into simpler ones)

EX: Copper, Gold, Oxygen, etc.

Atom

Basic unit of matter

Atomic Number

The number of protons (also equals number of electrons)

Atomic mass

Total mass of an atom

(# of protons + # of nuetrons)

Isotopes

Isotopes are atoms of the same element that have different numbers of neutrons, but the same number of protons.

Ions

An electrically charged atom/molecule

EX: An atom that has lost an electron is positively charged. An atom that gained an electron is negatively charged.

Independent variable

• The cause

• What you control or change in the experiment.

Dependent variable

• The effect

• What changes because of the independent variable (what you measure)

Qualitative data

• Observations

• Cannot be graphed

• Goes in a table

Quantitive data

• Numbers

• Can be graphed

Orbital

The area where an electron is likely to be found

(Orbitals closer to nucleus have less energy)

atomic mass - atomic # =

# of neutrons

Molecule

Two or more atoms joined together (by covalent bonds)

Compound

Two or more DIFFERENT elements (atoms) joined together

(All compounds are molecules, but not all molecules are compounds)

Shells

The energy levels around an atom’s nucleus where electrons are found.

• Rings around an atom’s center where electrons live.

  FACT: Each ring can hold a certain number of electrons.

  ring 1: 2

  ring 2: 8

  ring 3: 8

(The farther away a shell is the more potential energy it holds)

Chemical bond

An attraction between atoms that holds them together

Valance electrons

Electrons farthest from the nucleus (in the outermost orbitals of an atom)

(Highest energy level of the atom)

Molecular orbital (aka merged orbital)

A molecular orbital is like a merged orbital, formed when atomic orbitals from different atoms combine during bonding.

Covalent bond

A bond that holds merged orbitals together by sharing electrons between atoms

• They are strong and stable, requirring more energy to break compared to Ionic bonds)

remember these are bonds between atoms

Covalent bond structural formula

A line connecting two chemical symbols

Ionic bonds (aka non-covalent bonds)

Explanation: A bond formed when one atom gives away electrons and another takes them, so they stick together because of opposite charges.

🧠 How It Works:

1. One atom loses electrons
   → becomes positive (called a cation)

2. One atom gains electrons
   → becomes negative (called an anion)

3. Opposites attract
   → They stick together like magnets 🧲

(Electrons are transferred compared to covalent bonds which SHARE electrons)

remember these are bonds between atoms

Double bond

When two atoms share two pairs of electrons (4 elhappens when two atoms link up by sharing four outer electrons (two pairs) to stay together

remember these are bonds between atoms

Double bond structural formula

A double line connecting two chemical symbols for the atoms