Explain the properties of materials in terms of the arrangement and properties of the atoms that compose them.
3.1a The modern model of the atom has evolved over a long period of time through the work of many scientists.
3.1b Each atom has a nucleus, with an overall positive charge, surrounded by negatively charged electrons.
3.1c Subatomic particles contained in the nucleus include protons and neutrons.
3.1d The proton is positively charged, and the neutron has no charge. The electron is negatively charged.
3.1e Protons and electrons have equal but opposite charges. The number of protons equals the number of electrons in an atom.
Apply the principle of conservation of mass to chemical reactions.
3.3a In all chemical reactions there is a conservation of mass, energy, and charge.
3.3b In a redox reaction the number of electrons lost is equal to the number of electrons gained.
3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.
3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound.
3.3e The formula mass of a substance is the sum of the atomic masses of its atoms. The molar mass (gram-formula mass) of a substance equals one mole of that substance.
3.3f The percent composition by mass of each element in a compound can be calculated mathematically.
Explain chemical bonding in terms of the behavior of electrons.
5.2a Chemical bonds are formed when valence electrons are:
• transferred from one atom to another (ionic)
• shared between atoms (covalent)
• mobile within a metal (metallic)
5.2b Atoms attain a stable valence electron configuration by bonding with other atoms. Noble gases have stable valence configurations and tend not to bond.
5.2c When an atom gains one or more electrons, it becomes a negative ion and its radius increases. When an atom loses one or more electrons, it becomes a positive ion and its radius decreases.
5.2d Electron-dot diagrams (Lewis structures) can represent the valence electron arrangement in elements, compounds, and ions.
5.2e In a multiple covalent bond, more than one pair of electrons are shared between two atoms. Unsaturated organic compounds contain at least one double or triple bond.
5.2f Some elements exist in two or more forms in the same phase. These forms differ in their molecular or crystal structure, and hence in their properties.
Observe and describe transmission of various forms of energy.
4.1a Energy can exist in different forms, such as chemical, electrical, electromagnetic, thermal, mechanical, nuclear.
4.1b Chemical and physical changes can be exothermic or endothermic.
4.1c Energy released or absorbed during a chemical reaction can be represented by a potential energy diagram.
4.1d Energy released or absorbed during a chemical reaction (heat of reaction) is equal to the difference between the potential energy of the products and potential energy of the reactants.
Use kinetic molecular theory (KMT) to explain rates of reactions and the relationships among temperature, pressure, and volume of a substance.
3.4a The concept of an ideal gas is a model to explain the behavior of gases. A real gas is most like an ideal gas when the real gas is at low pressure and high temperature.
3.4b Kinetic molecular theory (KMT) for an ideal gas states that all gas particles:
• are in random, constant, straight-line motion.
• are separated by great distances relative to their size; the volume of the gas particles is considered negligible.
• have no attractive forces between them.
• have collisions that may result in a transfer of energy between gas particles, but the total energy of the system remains constant.
3.4c Kinetic molecular theory describes the relationships of pressure, volume, temperature, velocity, and frequency and force of collisions among gas molecules.
3.4d Collision theory states that a reaction is most likely to occur if reactant particles collide with the proper energy and orientation.
Use atomic and molecular models to explain common chemical reactions.
3.2a A physical change results in the rearrangement of existing particles in a substance. A chemical change results in the formation of different substances with changed properties.
3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement.
3.2c Types of organic reactions include addition, substitution, polymerization, esterification, fermentation, saponification, and combustion.
3.2d An oxidation-reduction (redox) reaction involves the transfer of electrons (e-).
3.2e Reduction is the gain of electrons.
3.2f A half-reaction can be written to represent reduction.
3.2g Oxidation is the loss of electrons.
3.2h A half-reaction can be written to represent oxidation.
Explain the benefits and risks of radioactivity.
4.4a Each radioactive isotope has a specific mode and rate of decay (half-life).
4.4b Nuclear reactions include natural and artificial transmutation, fission, and fusion.
4.4c Nuclear reactions can be represented by equations that include symbols which represent atomic nuclei (with mass number and atomic number), subatomic particles (with mass number and charge), and/or emissions such as gamma radiation.
4.4d Radioactive isotopes have many beneficial uses. Radioactive isotopes are used in medicine and industrial chemistry for radioactive dating, tracing chemical and biological processes, industrial measurement, nuclear power, and detection and treatment of diseases.
4.4e There are inherent risks associated with radioactivity and the use of radioactive isotopes. Risks can include biological exposure, long-term storage and disposal, and nuclear accidents.
4.4f There are benefits and risks associated with fission and fusion reactions.
Abstraction and symbolic representation are used to communicate mathematically.
Use algebraic and geometric representations to describe and compare data.
• organize, graph, and analyze data gathered from laboratory activities or other sources
â—† identify independent and dependent variables
â—† create appropriate axes with labels and scale
â—† identify graph points clearly
• measure and record experimental data and use data in calculations
â—† choose appropriate measurement scales and use units in recording
â—† show mathematical work, stating formula and steps for solution
â—† estimate answers
â—† use appropriate equations and significant digits
â—† show uncertainty in measurement by the use of significant figures
â—† identify relationships within variables from data tables
â—† calculate percent error
• recognize and convert various scales of measurement
◆ temperature [ Celsius (°C), Kelvin (K) ]
â—† length [ kilometers (km), meters (m), centimeters (cm), millimeters (mm)]
â—† mass [ grams (g), kilograms (kg) ]
â—† pressure [ kilopascal (kPa), atmosphere (atm) ]
• use knowledge of geometric arrangements to predict particle properties or behavior
Explain heat in terms of kinetic molecular theory.
4.2a Heat is a transfer of energy (usually thermal energy) from a body of higher temperature to a body of lower temperature. Thermal energy is the energy associated with the random motion of atoms and molecules.
4.2b Temperature is a measurement of the average kinetic energy of the particles in a sample of material. Temperature is not a form of energy.
4.2c The concepts of kinetic and potential energy can be used to explain physical processes that include: fusion (melting), solidification (freezing), vaporization (boiling, evaporation), condensation, sublimation, and deposition.
Compare energy relationships within an atom's nucleus to those outside the nucleus.
5.3a A change in the nucleus of an atom that converts it from one element to another is called transmutation. This can occur naturally or can be induced by the bombardment of the nucleus with high-energy particles.
5.3b Energy released in a nuclear reaction (fission or fusion) comes from the fractional amount of mass that is converted into energy. Nuclear changes convert matter into energy.
5.3c Energy released during nuclear reactions is much greater than the energy released during chemical reactions.
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