Chapter 3: States of Matter and Atomic Structure (Review)

A set of practice flashcards covering states of matter, Dalton’s atomic theory, atomic structure, isotopes/radioisotopes, and related concepts to help study for the exam.

What is matter?

Anything that takes up space; is made up of atoms.

What are the states of matter as temperature changes?

Solids have tightly packed molecules with little movement; melting turns solids into liquids with more movement; heating further yields gases with much more movement and lower density.

What happens to bonds when you heat something up?

Heat excites molecules, increasing movement until bonds break or denature, changing the material.

What is sublimation?

Solid changes directly to a gas without passing through the liquid phase.

Dalton’s first postulate

All matter is made up of atoms.

Dalton’s second postulate

Atoms of a given element have the same mass and properties.

Dalton’s third postulate

Compounds are a combination of two or more different atoms.

Dalton’s fourth postulate

In a chemical reaction, bonds are changed: formed, broken, or rearranged (RXN).

What is a molecule?

A group of atoms held together by bonds.

What is a compound?

A molecule that contains at least two different elements.

Is water (H2O) a compound?

Yes; it contains two different elements (hydrogen and oxygen) bonded together.

Is glucose (C6H12O6) a compound?

Yes; it contains carbon, hydrogen, and oxygen in a single molecule.

What is an isotope?

An element with a different number of neutrons, so mass differs; some isotopes are radioactive.

What is half-life?

The time required for a radioactive isotope to decay to half of its amount.

What is atomic mass?

Measured in atomic mass units (amu); protons and neutrons each weigh ~1 amu; electrons weigh almost nothing; mass reflects protons+neutrons and isotopic composition.

What is atomic number?

The number of protons in the nucleus; defines the element; neutral atoms have equal numbers of protons and electrons.

What is the difference between isotopes and radioisotopes?

Radioisotopes are unstable isotopes that decay and release energy; isotopes can be stable or unstable depending on neutrons.

What is the octet rule?

Atoms strive to have a full outer (valence) shell of eight electrons for stability.

What are valence electrons?

Electrons in the outermost shell; they determine an atom’s reactivity.

What are the major biologically important elements (CHON)?

Carbon, Hydrogen, Oxygen, and Nitrogen are the core elements in organic life; other key elements include phosphorus, potassium, sulfur, calcium, iodine, and iron.

Why is iodine important for the thyroid?

The thyroid requires iodine to produce hormones; iodine concentrates in the thyroid during treatment and must be managed for a period due to half-life.