General Biology Study Notes: Matter, Elements, and Atoms

Bio Notes 2.1: Matter and Elements

Introduction to Matter

All living and non-living things are composed of matter, which is the fundamental substance of the universe. Understanding matter is essential for studying biology, as it forms the basis of all biological structures and processes.

• Matter: Defined as anything that occupies space and has mass.

• Matter exists in three states: liquid, gas, and solid.

Elements and Compounds

Elements are the simplest forms of matter, while compounds are substances formed from two or more elements in fixed ratios.

• Element: A substance consisting of only one type of atom; cannot be broken down into simpler substances by chemical means.

• Compound: A substance consisting of two or more different elements combined in a fixed ratio. Compounds have characteristics different from those of their constituent elements.

• Most compounds contain at least 3 or 4 elements.

Essential Elements for Life

Living organisms require specific elements to survive and function. These elements are classified based on their abundance and necessity.

• Humans need 25 elements; plants need only 17.

• Trace elements: Elements essential to life but required in extremely small amounts.

Bio Notes 2.2: Trace Elements and Their Importance

Role of Trace Elements

Trace elements are vital for health, even though they are needed in minute quantities. Their deficiency can lead to significant health problems.

• Trace elements are sometimes difficult to fulfill in the diet.

• Examples of trace element deficiencies:

  • Iron deficiency: Can lead to anemia.

  • Iodine deficiency: Can cause thyroid problems.

• Trace element levels are monitored to improve public health.

Bio Notes 2.3: Atomic Structure and Properties

Atoms and Their Components

Atoms are the smallest units of matter that retain the properties of an element. Each element is defined by its unique type of atom.

• Atom: The smallest unit of matter that retains the properties of an element.

• Each element has its own type of atom, named from Greek words meaning "indivisible."

Subatomic Particles

Atoms are composed of subatomic particles, each with distinct properties.

• Proton: Subatomic particle with a single positive electrical charge.

• Electron: Subatomic particle with a single negative electrical charge.

• Neutron: Electrically neutral subatomic particle; has no charge.

Atomic Number and Mass Number

Atoms are characterized by their atomic number and mass number, which determine their identity and mass.

• Atomic number: Number of protons in each atom of a particular element.

• Mass number: Sum of protons and neutrons in an atom's nucleus.

• Atomic mass: The total mass of an atom, usually measured in atomic mass units (amu).

Isotopes and Radioactivity

Isotopes are variants of elements with different numbers of neutrons. Some isotopes are radioactive and have important biological and medical applications.

• Isotope: One of several atomic forms of an element, each with the same number of protons but a different number of neutrons.

• Radioactive isotope: An isotope whose nucleus decays spontaneously, giving off particles and energy.

Table: Comparison of Subatomic Particles

Particle	Charge	Location
Proton	+1	Nucleus
Neutron	0	Nucleus
Electron	-1	Electron cloud (outside nucleus)

Key Equations

• Atomic number: $\text{Atomic number} = \text{Number of protons}$

• Mass number: $\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$

Examples and Applications

• Iron is a trace element essential for oxygen transport in blood.

• Iodine is required for thyroid hormone production.

• Radioactive isotopes are used in medical imaging and cancer treatment.