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- Standard - MST4: Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.
- Key Idea Code - MST4.PS:
- Key Idea - MST4.PS3: Matter is made up of particles whose properties determine the observable characteristics of matter and its reactivity.
- Academic Level - MST4.C.PS3:
- Course - MST4.C.PS3.CH:
- Performance Indicator - MST4.C.PS3.CH.A: Students explain the properties of materials in terms of the arrangement and properties of the atoms that compose them.
- Major Understandings - 3.1a : The modern model of the atom has evolved over a long period of time through the work of many scientists.
- Major Understandings - 3.1b : Each atom has a nucleus, with an overall positive charge, surrounded by negatively charged electrons.
- Major Understandings - 3.1c : Subatomic particles contained in the nucleus include protons and neutrons.
- Major Understandings - 3.1d : The proton is positively charged, and the neutron has no charge. The electron is negatively charged.
- Major Understandings - 3.1e : Protons and electrons have equal but opposite charges. The number of protons equals the number of electrons in an atom.
- Major Understandings - 3.1f : The mass of each proton and each neutron is approximately equal to one atomic mass unit. An electron is much less massive than a proton or a neutron.
- Major Understandings - 3.1g : The number of protons in an atom (atomic number) identifies the element. The sum of the protons and neutrons in an atom (mass number) identifies an isotope. Common notations that represent isotopes include:
carbon-14, C-14. - Major Understandings - 3.1h : In the wave-mechanical model (electron cloud model) the electrons are in orbitals, which are defined as the regions of the most probable electron location (ground state).
- Major Understandings - 3.1i : Each electron in an atom has its own distinct amount of energy.
- Major Understandings - 3.1j : When an electron in an atom gains a specific amount of energy, the electron is at a higher energy state (excited state).
- Major Understandings - 3.1k : When an electron returns from a higher energy state to a lower energy state, a specific amount of energy is emitted. This emitted energy can be used to identify an element.
- Major Understandings - 3.1l : The outermost electrons in an atom are called the valence electrons. In general, the number of valence electrons affects the chemical properties of an element.
- Major Understandings - 3.1m : Atoms of an element that contain the same number of protons but a different number of neutrons are called isotopes of that element.
- Major Understandings - 3.1n : The average atomic mass of an element is the weighted average of the masses of its naturally occurring isotopes.
- Major Understandings - 3.1o : Stability of an isotope is based on the ratio of neutrons and protons in its nucleus.
Although most nuclei are stable, some are unstable and spontaneously decay, emitting radiation.
- Major Understandings - 3.1p : Spontaneous decay can involve the release of alpha particles, beta particles, positrons, and/or gamma radiation from the nucleus of an unstable isotope. These emissions differ in mass, charge, ionizing power, and penetrating power.
- Major Understandings - 3.1q : Matter is classified as a pure substance or as a mixture of substances.
- Major Understandings - 3.1r : A pure substance (element or compound) has a constant composition and constant properties throughout a given sample, and from sample to sample.
- Major Understandings - 3.1s : Mixtures are composed of two or more different substances that can be separated by physical means. When different substances are mixed together, a homogeneous or heterogeneous mixture is formed.
- Major Understandings - 3.1t : The proportions of components in a mixture can be varied. Each component in a mixture retains its original properties.
- Major Understandings - 3.1u : Elements are substances that are composed of atoms that have the same atomic number. Elements cannot be broken down by chemical change.
- Major Understandings - 3.1v : Elements can be classified by their properties and located on the Periodic Table as metals, nonmetals, metalloids (B, Si, Ge, As, Sb, Te), and noble gases.
- Major Understandings - 3.1w : Elements can be differentiated by physical properties. Physical properties of substances, such as density, conductivity, malleability, solubility, and hardness, differ among elements.
- Major Understandings - 3.1x : Elements can also be differentiated by chemical properties. Chemical properties describe how an element behaves during a chemical reaction.
- Major Understandings - 3.1y : The placement or location of an element on the Periodic Table gives an indication of the physical and chemical properties of that element. The elements on the Periodic Table are arranged in order of increasing atomic number.
- Major Understandings - 3.1z : For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence electrons (helium is an exception) and therefore similar chemical properties.
- Major Understandings - 3.1aa: The succession of elements within the same group demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties.
- Major Understandings - 3.1bb: The succession of elements across the same period demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties.
- Major Understandings - 3.1cc: A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system.
- Major Understandings - 3.1dd: Compounds can be differentiated by their physical and chemical properties.
- Major Understandings - 3.1ee: Types of chemical formulas include empirical, molecular, and structural.
- Major Understandings - 3.1ff: Organic compounds contain carbon atoms, which bond to one another in chains, rings, and networks to form a variety of structures. Organic compounds can be named using the IUPAC system.
- Major Understandings - 3.1gg: Hydrocarbons are compounds that contain only carbon and hydrogen. Saturated hydrocarbons contain only single carbon-carbon bonds. Unsaturated hydrocarbons contain at least one multiple carbon-carbon bond.
- Major Understandings - 3.1hh: Organic acids, alcohols, esters, aldehydes, ketones, ethers, halides, amines, amides, and amino acids are categories of organic compounds that differ in their structures. Functional groups impart distinctive physical and chemical properties to organic compounds.
- Major Understandings - 3.1ii: Isomers of organic compounds have the same molecular formula, but different structures and properties.
- Major Understandings - 3.1jj: The structure and arrangement of particles and their interactions determine the physical state of a substance at a given temperature and pressure.
- Major Understandings - 3.1kk: The three phases of matter (solids, liquids, and gases) have different properties.
- Major Understandings - 3.1ll: Entropy is a measure of the randomness or disorder of a system. A system with greater disorder has greater entropy.
- Major Understandings - 3.1mm: Systems in nature tend to undergo changes toward lower energy and higher entropy.
- Major Understandings - 3.1nn: Differences in properties such as density, particle size, molecular polarity, boiling and freezing points, and solubility permit physical separation of the components of the mixture.
- Major Understandings - 3.1oo: A solution is a homogeneous mixture of a solute dissolved in a solvent. The solubility of a solute in a given amount of solvent is dependent on the temperature, the pressure, and the chemical natures of the solute and solvent.
- Major Understandings - 3.1pp: The concentration of a solution may be expressed in molarity (M), percent by volume, percent by mass, or parts per million (ppm).
- Major Understandings - 3.1qq: The addition of a nonvolatile solute to a solvent causes the boiling point of the solvent to increase and the freezing point of the solvent to decrease. The greater the concentration of solute particles, the greater the effect.
- Major Understandings - 3.1rr: An electrolyte is a substance which, when dissolved in water, forms a solution capable of conducting an electric current. The ability of a solution to conduct an electric current depends on the concentration of ions.
- Major Understandings - 3.1ss: The acidity or alkalinity of an aqueous solution can be measured by its pH value.
The relative level of acidity or alkalinity of these solutions can be shown by using indicators.
- Major Understandings - 3.1tt: On the pH scale, each decrease of one unit of pH represents a tenfold increase in
hydronium ion concentration.
- Major Understandings - 3.1uu: Behavior of many acids and bases can be explained by the Arrhenius theory. Arrhenius acids and bases are electrolytes.
- Major Understandings - 3.1vv: Arrhenius acids yield H+(aq), hydrogen ion as the only positive ion in an aqueous solution. The hydrogen ion may also be written as H3O+(aq), hydronium ion.
- Major Understandings - 3.1ww: Arrhenius bases yield OH-(aq), hydroxide ion as the only negative ion in an aqueous solution.
- Major Understandings - 3.1xx: In the process of neutralization, an Arrhenius acid and an Arrhenius base react to form a salt and water.
- Major Understandings - 3.1yy: There are alternate acid-base theories. One theory states that an acid is an H+ donor and a base is an H+ acceptor.
- Major Understandings - 3.1zz: Titration is a laboratory process in which a volume of a solution of known concentration is used to determine the concentration of another solution.
