Periodic Trends Part I

Students explore the relationship between the properties of an atom and its location on the periodic table as well as about effective nuclear charge and electronegativity.

The students create their own Bohr models and learn about effective nuclear charge in this segment.

Premiere Date: July 10, 2016 | Runtime: 00:12:12

## Toolkit

Bohr Model Diagram
List of Elements With Properties
Unit 3D Note Taking Guide Segment Questions

## Crosscutting Concepts

System and System Models

Defining the system under study—specifying its boundaries and making explicit a model of that system—provides tools for understanding and testing ideas that are applicable throughout science and engineering.

Patterns

Observed patterns of forms and events guide organization and classification, and they prompt questions about relationships and the factors that influence them.

Cause and Effect

Mechanism and explanation. Events have causes, sometimes simple, sometimes multifaceted. A major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts.

## Science & Engineering Practices

Constructing Explanations and Designing Solutions

The goal of science is the construction of theories that provide explanatory accounts of the world. A theory becomes accepted when it has multiple lines of empirical evidence and greater explanatory power of phenomena than previous theories.”(NRC Framework, 2012, p. 52)

Engaging in Argument from Evidence

The study of science and engineering should produce a sense of the process of argument necessary for advancing and defending a new idea or an explanation of a phenomenon and the norms for conducting such arguments. In that spirit, students should argue for the explanations they construct, defend their interpretations of the associated data, and advocate for the designs they propose. (NRC Framework, 2012, p. 73)

Generating a Hypothesis and Developing a Model

Modeling can begin in the earliest grades, with students’ models progressing from concrete “pictures” and/or physical scale models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system. (NRC Framework, 2012, p. 58)

## Vocabulary

anion - a negatively charged ion.

atomic number - the number of protons in the nucleus of an atom.

atomic radius - the distance from the atom's nucleus to the outermost energy level.

average atomic mass - a weighted average of all of the isotopes of that element in the universe.

cation - a positively charged ion.

effective nuclear charge (Zsubeff) - the net positive charge experienced by the valence electrons from the nucleus.

electron - a tiny particle with a negative charge that is found outside the nucleus of an atom.

electron configuration - the order in which electrons are arranged in an atom.

electronegativity - the ability of an atom to attract additional electrons.

energy sublevel - a smaller part within a primary energy level.

excited state - an atom, ion or molecule with an electron in a higher than normal energy level than its ground state.

ground state - the lowest energy state within electron orbitals.

Hund's Rule - When placing electrons in equal energy orbitals, electrons should not be paired until each equal energy orbital contains one electron.

ion - an atom with a positive or negative charge.

ionization energy - the amount of energy required to remove one valence electron from an atom.

isotope - the same element with different numbers of neutrons.

model - a physical, conceptual, or mathematical representation of a real phenomenon whose purpose is to explain and predict the observed phenomenon.

orbital - a region of space around the nucleus of an atom where an electron is likely to be found.

Pauli exclusion principle - when an orbital holds two electrons, the electrons much have opposite spin.

quantum - a specific amount of energy that can be absorbed by an electron as it moves from ground state to excited state, or released by an electron as it falls from the excited state back to ground state.

subatomic- any smaller part of an atom such as a proton, neutron, or electron.

valence electrons - electrons on the outer-most energy level of any atom.

valence shell - the outer-most energy level of an electron.

## Georgia Standards of Excellence

SC1Obtain, evaluate, and communicate information about the use of the modern atomic theory and periodic law to explain the characteristics of atoms and elements.

SC1.aEvaluate the merits and limitations of different models of the atom in relation to relative size, charge, and position of protons, neutrons, and electrons in the atom.

SC1.bConstruct an argument to support the claim that the proton (and not the neutron or electron) defines the element’s identity.

SC1.fUse the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms (including atomic radii, ionization energy, and electronegativity of various elements).

SC1.gDevelop and use models including electron configuration of atoms and ions to predict an element’s chemical properties.

SPS1Obtain, evaluate, and communicate information from the Periodic Table to explain the relative properties of elements based on patterns of atomic structure.

SPS1.aDevelop and use models to compare and contrast the structure of atoms, ions and isotopes.
(Clarification statement: Properties include atomic number, atomic mass and the location and charge of subatomic particles.)

SPS1.bAnalyze and interpret data to determine trends of the following:
• number of valence electrons
• types of ions formed by main group elements
• location and properties of metals, nonmetals, and metalloids
• phases at room temperature

SPS1.cUse the Periodic Table as a model to predict the above properties of main group elements.

S8P1Obtain, evaluate, and communicate information about the structure and properties of matter.

S8P1.eDevelop models (e.g., atomic-level models, including drawings, and computer representations) by analyzing patterns within the periodic table that illustrate the structure, composition, and characteristics of atoms (including protons, neutrons, and electrons) and simple molecules.

## Request Teacher Toolkit

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