Is Chemistry Required in High School in Kansas?
In order to graduate from high school in Kansas, students must achieve (3) three units of science, which shall include physical, biological, and earth and space science concepts and which shall include at least one unit as a laboratory course. If the student is pursuing a Scholars Diploma, they must achieve 3 years of science with one year each in Biology, Chemistry, and Physics, each of which includes an average of one laboratory period a week.
Kansas is a Next-Generation Science Standards (NGSS) lead state, which means they played a pivotal role in designing the common core curriculum many states use to guide their science education standards. Starting in Grade 8, chemistry subjects that students will explore include:
STANDARD 2A: CHEMISTRY
Benchmark 1: The student will understand the structure of the atom.
The student will develop an understanding of the structure of atoms, compounds, chemical reactions, and the interactions of energy and matter. The student …
- 1. Understands atoms, the fundamental organizational unit of matter, are composed of subatomic particles. Chemists are primarily interested in the protons, electrons, and neutrons found in the atom.
- 1a. All atoms are identified by the number of protons in the nucleus, i.e. the atomic number. The protons have a positive charge and a mass of 1 amu. Protons and neutrons are found in the small, dense, nucleus.
- 1b. Neutrons have a neutral charge and a mass of 1 amu.
- 1c. The electrons have a negative charge and are found outside the nucleus in an electron cloud. The mass of an electron is approximately 2,000 times smaller than a proton. The electrons determine the size and chemical properties of the atom.
- 1d. The number of electrons is equal to the number of protons in a neutral atom. Ions have a different number of electrons than protons.
- 2. Understands isotopes are atoms with the same atomic number (same number of protons) but different numbers of neutrons. The nuclei of some atoms are radioactive isotopes that spontaneously decay, releasing radioactive energy.
- 2 a. The periodic table reflects the average mass of the isotopes.
- 2b. Examples of released radioactivity are alpha, beta, and gamma radiation.
- 2c. Some isotopes spontaneously decay at a first-order rate. There is a negative linear relationship between the log of the sample isotope concentration vs. time,
- 2d. To balance a nuclear equation, the sum of the atomic numbers and the sum of the mass numbers must be equal on both sides of the equation.
Benchmark 2: The students will understand the states and properties of matter.
The student will develop an understanding of the structure of atoms, compounds, chemical reactions, and the interactions of energy and matter. The student …
- 1. Understands chemists use kinetic and potential energy to explain the physical and chemical properties of matter on earth that may exist in any of these three states: solids, liquids, and gases.
- 1a. Elements and molecules may exist as gases, liquids, or solids. Ionic compounds most commonly exist as solids.
- 1b. Intermolecular attraction (attraction between molecules) determines the state of the molecule. Examples of intermolecular attraction include hydrogen bonding, permanent dipole interaction, and induced dipole interaction. Gases have the weakest and solids have the greatest intermolecular attraction. The hydrogen bond is an intermolecular attraction responsible for the properties of water and many biological molecules.
- 2. Understands the periodic table lists elements according to increasing atomic number. This table organizes physical and chemical trends by groups, periods, and sub-categories.
- 2a. Elements in the same group have the same number of valence electrons and can be used to predict similar physical and chemical properties. Elements are grouped by similar ground state valence electron configurations.
- 2b. As periods increase, the principle energy levels of the outermost (valence) electrons increase Electrons changing from one energy level to another may result in the emission or absorption of various forms of electromagnetic radiation, including the range of colors that form visible light. When there is color, there are electrons changing energy levels.
- 2c. Sub-categories are regions such as metals, non-metals, and transition elements. Nonmetals have different physical and chemical properties than metals. For example, nonmetals have lower melting points, lower density, and are poorer conductors of electricity and heat. Chemical properties depend on the subshell of the valence electrons which are different for metals and non-metals.
- 3. Understands theories of bonding, chemical bonds result when valence electrons are transferred or shared between atoms. Breaking a chemical bond requires energy. Formation of a chemical bond releases energy. Ionic compounds result from atoms transferring electrons. Molecular compounds result from atoms sharing electrons. For example, carbon atoms can bond to each other in chains, rings, and branching networks. Branched network and metallic solids also result from bonding.
- 3a. Valence electron configurations determine whether an atom gains, loses, or shares electrons to achieve a more stable electron configuration similar to the noble gases.
- 3b. Positively charged ions are called cations, and negatively charged ions are called anions. Cations are attracted to anions (opposite charges attract). Most cations are metals; most anions are nonmetals. In stable ionic compounds, the sum of the charges is zero.
- 3c. Covalent bonds form when two or more atoms share one or more pairs of electrons to achieve a more stable electron configuration. The two classifications of covalent bonds are nonpolar and polar. The greater the electronegativity difference between atoms involved in the bond, the more polar the bond.
- 3d. The energy required to break ionic bonds is greater than the energy required to break covalent bonds. Heat exchange during a chemical reaction is often easily noticed: a reaction that absorbs heat will feel colder; a reaction that releases heat will feel warmer.
- 3e. Carbon atoms can bond to each other in chains, rings, and branching networks to form a variety of molecular structures including relatively large molecules essential to life. Diamonds, a 3-dimensional branching of carbon atoms and quartz, a repeated 3-dimensional branching of silicon dioxide molecules, are further examples of network solids. Unique properties of network solids include hardness, high melting points, poor conductors - indicative of covalent bonding and stable geometry.
- 3f. Metallic bonding is defined as free-roaming electrons forming a negative sea of electrons surrounding the positive metal ions.
Benchmark 3: The student will gain a basic concept of chemical reactions.
The students will develop an understanding of the structure of atoms, compounds, chemical reactions, and the interactions of energy and matter. The student …
- 1. Understands a chemical reaction occurs when one or more substances (reactants) react to form a different chemical substance(s) (products). There are different types of chemical reactions all of which demonstrate the Law of Conservation of Matter and Energy.
- 1a. Chemical reactions are written as balanced chemical equations. In ordinary chemical reactions, the number and kind of atoms must be conserved.
- 1b. Examples of chemical reactions are synthesis, decomposition, combustion, single and double replacement, acid/base, and oxidation/reduction.
- 1c. Two or more of the following may often identify chemical reactions: physical property change, effervescence, mass change, precipitation, light emission, and heat exchange.
- 1d. The rate (speed) of a chemical reaction depends on such parameters as temperature, concentration, catalysts, inhibitors, surface area, and reaction type.
- 2. understands how to perform mathematical calculations regarding the Law of Conservation of Matter, i.e., through stoichiometric relationships.
- 2a. Reaction stoichiometry involves understanding the use of coefficients (moles) to balance equations and solve for a variety of relationships using the molar mass of the substances. Examples of these types of relationships include mole/mole, mole/mass, mole/volume, mass/volume, mass/mass, etc.
- 3. Understands the differences and reactions between acids, bases, and salts. Perform calculations to determine the concentration of ions in solutions.
- 3a. Acids react with bases to produce water and salt.
- 3b. pH is a logarithmic function of hydronium ion concentration. pH decreases as the hydronium ion concentration increases. pOH and hydroxide concentrations are found in a similar way.