Define the following:

Question

i. Atomic number
ii. Atomic mass/weight
c. When examining the human body, we find that we are composed of 25
different elements. Of those elements, only 4 make up approximately 96%
of us! Using the image on the next page, list the “Big 4” elements here.
● Element 1:
● Element 2:
● Element 3:
● Element 4:
5 Phelan, What is Life, 5e, 2021,© W. H. Freeman and Company

Answer 1

i. Atomic Number: The atomic number of an element is the number of protons found in the nucleus of an atom of that element. It is unique to each element and determines the element's identity and its position in the periodic table. For example, hydrogen has an atomic number of 1, while carbon has an atomic number of 6.

ii. Atomic Mass/Weight: Atomic mass (or atomic weight) is the weighted average mass of an atom of an element, measured in atomic mass units (amu). It reflects the mass of an atom, taking into account the number of protons and neutrons in the nucleus, and the relative abundance of different isotopes of the element. It is not a whole number because it represents an average that includes all isotopes of the element.

c. The “Big 4” elements that make up approximately 96% of the human body are:

● Element 1: Oxygen
● Element 2: Carbon
● Element 3: Hydrogen
● Element 4: Nitrogen