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The Nucleus: Crash Course Chemistry #1

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The Nucleus: Crash Course Chemistry #1


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Chemistry can tell us how three tiny particles--the proton, neutron, and electron--come together in trillions of combinations to form everything. In this inaugural episode of Crash Course Chemistry, we start out with one of the biggest ideas in chemistry ever--stuff is made from atoms. More specifically, we learn about the properties of the nucleus and why they are important to defining what an atom actually is.

Content Standard(s):
SC2015 (2015)
Grade: 9-12
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.

NAEP Framework
NAEP Statement::
P12.4: In a neutral atom, the positively charged nucleus is surrounded by the same number of negatively charged electrons. Atoms of an element whose nuclei have different numbers of neutrons are called isotopes.

Unpacked Content
Scientific And Engineering Practices:
Developing and Using Models
Crosscutting Concepts: Scale, Proportion, and Quantity
Disciplinary Core Idea: Matter and Its Interactions
Evidence Of Student Attainment:
  • Identify isotopes of elements.
  • Develop a model that relates the published atomic mass of an element on the periodic table to the abundance of that element's isotopes.
  • Use the model to determine the most common isotopic form of an element in nature.
Teacher Vocabulary:
  • Atomic mass
  • Isotopes
  • Abundance
  • Weighted average
  • Nucleus
  • Protons
  • Neutrons
  • Macroscopic level
  • Atomic/ molecular/ particulate level
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.
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.
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.
AMSTI Resources:
ASIM Module:
Calculating Average Atomic Mass Coinium Isotopes of Atoms, Coinium Isotopes of Atoms
Tags: atom, chemistry, electron, neutron, nucleus, proton
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Author: Stephanie Carver