Textbook Chapter 2

Question 1

Matter definition

Answer 1

Organisms are composed of matter, which is anything that takes up space and and has mass. Matter exists in many forms. Rocks, metals, oils and gases and living organisms are examples of matter.

Question 2

Element defintion

Answer 2

Matter is made up of elements. An element is a substance that cannot be broken down down into other substances by chemical reactions. Today there are 92 recognized elements occurring in nature.

Question 3

Compound definition

Answer 3

A compound is a substance that consists of two or more different elements in a fixed ratio. Table salt or NaCl has a fixed ratio of 1:1. Water of H2O consists hydrogen and oxygen in a 2:1 ratio. These simple examples are examples of organized matter having emergent properties, compounds have different properties than elements.

Question 4

Essential elements for life

Answer 4

Of the total 92, only 20-25% are essential elements that an organism needs to live a healthy life and reproduce. The essential elements are similar among organisms but there is variation. Humans need 25 however plants only need 17.

Oxygen, Hydrogen, Nitrogen and Carbon make up 96% of living matter.

Question 5

Trace elements

Answer 5

Ca, P, K, S and a few other elements account for the missing 4% of an organism’s mass. Trace elements are only required in minute quantities in an organism. some like iron (Fe) are required by all life forms, others are only required by certain species. Iodine for example is only required in vertebrates.

Question 6

Element properties and atoms

Answer 6

Each element consists of atoms that are different from the atom of any other element. An atom is the smallest unit of matter that still retains the properties of an element.

Question 7

Subatomic particles