Unit 1

Chapter Overview

During this unit, students review and extend their understanding of the physical and chemical properties of matter, as manifested in elements, compounds, and mixtures.  Students explore elements and isotopes and then calculate average atomic mass.  They investigate the development of the modern theory of the atom, including the historical work of the scientists involved and how the basic structure of the atom was developed. 

Main Ideas

1. Analysis of the relationships between physical and chemical changes and properties is essential to understanding the nature of matter.

• How are the properties of matter distinguished?

• Why is the investigation and analysis of matter essential to the study of chemistry?

• In what ways are properties used to classify matter?

• How are changes in matter analyzed?

2. The historic scientific discoveries of the nature of the atom have fundamentally changed scientific understanding of the nature of matter.

• In what ways can analysis of the atom further define our understanding of the chemical and physical properties of matter?

• How has each historic scientific discovery changed our understanding of the chemical and physical properties of matter and our use of the Periodic Table?

• In what ways can the Periodic Table be used to demonstrate chemical and physical patterns?

3. Mathematical relationships exist between properties of light.

• In what ways can mathematical relationships between properties of light be demonstrated?

Misconceptions

• Students may think mass and weight are the same, rather than understanding that mass is the amount of matter in an object or substance and weight is a

• measure of the force of gravity on that matter or substance.

• Students may think a single observable change in properties, such as heat being given off or absorbed, is enough to indicate a chemical change.

• Students may think objects with larger volumes always have more mass.

• Students may think air and other gases do not have mass or weight.

• Students may not understand mass-volume relationships (density) as well as measuring and calculating density.

• Students may not understand that a sample of matter is either a pure substance or a mixture of pure substances.

• Students may not understand there is more than one model of the atom.

Vocabulary

• Matter – anything that has mass and takes up space

• Structure – arrangement of bonds between atoms in a molecule

• Pure Substance – substances that are made of only one type of atom or only one type of molecule  

• Element – substance that cannot be broken down into simpler substances by chemical means

• Molecule – a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction

• Compound – a substance formed when two or more chemical elements are chemically bonded together

• Mixture – substance made of two or more different substances that are mixed but are not chemically combined

• Solution – mixture with two or more substances

• Decant – separation of mixtures by removing a layer of liquid

• Distillation – separating the parts of a liquid by boiling it and then condensing the vapor that results

• Filtration – separation of solids from fluids by adding a medium through which only the fluid can pass

• Physical Property – a characteristic of a pure substance that can be observed or measured without changing the substance’s chemical identity

• Compressibility – the measure of how much a given volume of matter decreases when placed under pressure

• Density – the ration between mass and volume (d=m/v)

• Bohr Atom – the simplest picture of the structure of the atom, electrons orbit around the nucleus

• Dalton’s Postulates – theory with five parts that explain matter in terms of atoms and their properties

• Atom – smallest component of an element, shares the chemical properties of the element

• Protons – subatomic particle found in the nucleus, positive charge

• Neutrons – subatomic particle found in the nucleus, has no charge

• Nucleus – central part of the atom, contains protons and neutrons

• Electrons – smallest particle of the atom, negative charge

• Valence Electrons – those electrons involved in the formation of chemical bonds

• Atomic Number – number of protons in the nucleus of an atom, determines its place on the periodic table

• Isotopes – atoms of an element that have the same atomic number (protons) but different mass numbers due to different numbers of neutrons in their nuclei

• Hyphen Notation – a way of designating the isotopes of an element using its name (or symbol), a hyphen, and the mass number (ex: uranium-238)

• Mass Number – total number of protons and neutrons in an atomic nucleus

• Average Atomic Mass – sum of the masses of an element’s isotopes multiplied by its natural abundance

• Volume – amount of space occupied by a substance

• Physical Change – a change that alters a substance without changing its chemical composition or its identity

• Evaporation – process of a substance in liquid state changing to a gaseous state

• Sublimation – substance changes from a solid to a gas without passing through the liquid phase

• Vaporization – substance changes from the liquid to gaseous state

• Chemical Property – a characteristic of a pure substance that describes how it interacts with other substances

• Chemical Change – a change in the chemical composition and the identity of a substance

• Reactivity – tendency of a substance to undergo chemical changes

• Solubility – degree to which a substance dissolves in a solvent to make a solution

• Excited State – state in which an atom or molecule picks up energy, causing an electron to move into a higher-energy orbital

• Ground State – the lowest allowed energy state of an atom, molecule, or ion

• Atomic Emission Spectrum – the variety of frequencies of electromagnetic radiation (light) seen through a spectroscope that are emitted by electrons as they transition from higher to lower energy levels; unique for each element

• Electromagnetic Spectrum – all of the frequencies of electromagnetic radiation or light

• Frequency – the number of cycles of an event per unit time; one Hertz (Hz) means one cycle per second

• Planck’s Constant – a constant value that relates the energy of a photon of light to its frequency

• Wavelength – the length between successive peaks (or troughs) of a wave

• Spectroscope – instrument used to analyze the component parts of a sample by separating its parts into a spectrum

Notes

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