SC15.CHM.2
Develop and use models of atomic nuclei to explain why the abundance-weighted average of isotopes of an element yields the published atomic mass.
Develop and use models of atomic nuclei to explain why the abundance-weighted average of isotopes of an element yields the published atomic mass.
UP:SC15.CHM.2
Vocabulary
- Atomic mass
- Isotopes
- Abundance
- Weighted average
- Nucleus
- Protons
- Neutrons
- Macroscopic level
- Atomic/ molecular/ particulate level
Knowledge
Students know:
- Each atom has a charge substructure that consists of a nucleus, which is made of protons and neutrons, surrounded by electrons.
- The majority of an atom's mass comes from the protons and neutrons in the nucleus.
- Electrons have a very small mass, so they are not typically included in atomic mass calculations.
- Atoms of an element can have different masses, and we call those atoms isotopes.
- Isotopes of a given element have the same number of protons, but different number of neutrons.
- Most elements exist in nature in isotopic form.
Skills
Students are able to:
- Develop a model based on evidence to illustrate the relationship between the structure of the atom and the average atomic mass of an element.
- Use the model to make predictions.
- Calculate weighted averages.
- Determine the most common isotopic form of an element in nature.
Understanding
Students understand that:
- Models can be computational or mathematical.
- The published atomic mass of an element is a weighted average of all known isotopes of that element.
- Macroscopic patterns are related to the nature of atomic/ molecular/ particulate level structure.
Scientific and Engineering Practices
Developing and Using Models
Crosscutting Concepts
Scale, Proportion, and Quantity
