Introduction to Matter, Elements, and Compounds (Bio Notes 2.1)

Bio Notes 2.1: Matter, Elements, and Compounds

Introduction to Matter

All living and non-living things are composed of matter. Understanding the basic properties of matter is fundamental to the study of biology.

• Matter is defined as anything that occupies space and has mass.

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

• All things, including living organisms, are made of matter.

Elements

An element is a pure substance that cannot be broken down into other substances by chemical means. Elements are the building blocks of matter.

• Element: A substance consisting of atoms with the same number of protons.

• Each element has unique properties and is represented by a chemical symbol (e.g., H for hydrogen, O for oxygen).

• There are about 92 naturally occurring elements on Earth.

• Humans require 25 elements for life, while plants need only 17.

• Trace elements: Elements that are essential to life but required in extremely small amounts (e.g., iron, iodine).

Compounds

Compounds are substances formed when two or more different elements combine in a fixed ratio. Compounds have unique properties that are different from the elements that compose them.

• Compound: A substance consisting of two or more different elements combined in a fixed ratio.

• Compounds have characteristics distinct from those of their constituent elements.

• Most compounds in living organisms contain at least three or four different elements.

• Example: Water (H2O) is a compound made from hydrogen and oxygen.

Key Terms and Definitions

• Matter: Anything that has mass and takes up space.

• Element: A pure substance made of only one kind of atom.

• Compound: A substance made of two or more elements in a fixed ratio.

• Trace element: An element required by an organism in minute quantities.

Summary Table: Elements and Compounds

Term	Definition	Example
Matter	Anything that occupies space and has mass	Water, air, rocks
Element	Pure substance consisting of one type of atom	Oxygen (O), Carbon (C)
Compound	Substance formed from two or more elements in a fixed ratio	Water (H2O), Carbon dioxide (CO2)
Trace Element	Element required in very small amounts for life	Iodine (I), Iron (Fe)

Additional info:

• Elements are organized in the periodic table based on their atomic number.

• Compounds are held together by chemical bonds, such as covalent or ionic bonds.