2.1 Atoms Make Up All Matter

Atoms Make Up All Matter

• Matter is any material that takes up space (e.g., organisms, rocks, oceans, gases).

• Energy is defined as the ability to do work, related to moving matter.

• Chapters 4, 5, and 6 will elaborate on the energy of life.

A. Elements Are Fundamental Types of Matter

• Matter is composed of one or more elements.

• Chemical elements are pure substances that cannot be broken down chemically (e.g., oxygen (O), hydrogen (H), carbon (C)).

• Dmitry Mendeleyev created the periodic table to categorize elements based on their chemical properties.

• The periodic table showcases elements in vertical columns with repeating properties.

• Important Elements: Carbon, Hydrogen, Oxygen, Nitrogen (96% of human body), along with other bulk and trace elements.

Page 2 Details

• Abundant Elements:

  • Hydrogen (H)

  • Carbon (C)

  • Nitrogen (N)

  • Oxygen (O)

• Bulk elements lead to a majority of every living cell.

• Trace Elements: Include Iron (Fe) and Zinc (Zn), needed in small amounts (0.5% of body).

• Needing essential elements in diet prevents illnesses; e.g., iodine for thyroid function (goiter), iron for oxygen transport (anemia).

B. Atoms Are Particles of Elements

• An atom is the smallest piece of an element maintaining its characteristics.

• Atoms consist of three particle types:

  • Protons (positive charge)

  • Neutrons (no charge)

  • Electrons (negative charge, essentially weightless).

• Electrons form a surrounding cloud around the nucleus containing protons and neutrons.

Page 3 Details: Atom Structure

• Nucleus Composition: Protons and Neutrons.

• Charge Balance: When protons equal electrons, the atom is neutral.

• Ions: Atoms gaining/losing electrons acquire a net charge (e.g., H+, Na+).

• Ion functions include biological processes and forming ionic bonds.

C. Isotopes Have Different Numbers of Neutrons

• Mass number is the sum of protons and neutrons in the nucleus.

• Isotopes represent variations in neutrons; e.g., carbon has 12C, 13C, 14C with differing neutron counts.

Page 4 Details: Isotope Properties

• Common isotopes of carbon:

  • Carbon-12 (12C) - 6 protons, 6 neutrons

  • Carbon-13 (13C) - 6 protons, 7 neutrons

  • Carbon-14 (14C) - 6 protons, 8 neutrons

• Atomic weight reflects an average mass close to the most common isotope's mass.

Page 5 Details: Radioactive Isotopes

• Radioactive isotopes emit energy as they decay.

• Half-life terminology indicates the time for half of a sample to decay.

• Applications in medicine and science include using isotopes for diagnostics and dating fossils.

• Risks of radioactive exposure include sickness and potential mutations leading to cancer.

Page 6: Miniglossary

• Matter: Material taking up space.

• Element: Pure substance, can't be broken down.

• Atom: Smallest unit retaining element characteristics.

• Atomic Number: Count of protons in nucleus.

• Mass Number: Total protons + neutrons.

• Isotope: Variants of elements differing in neutron count.

• Radioactive Isotope: Atom that emits radiation due to decay.

• Atomic Weight: Average mass of element's atoms.