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Science Review Notes for Parents and Students Grade 8 Science 2nd Nine Weeks, 2012-2013
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Science Content Review: Standards of Learning in Detail Grade 8 Science: 2nd Nine Weeks 2012-2013
This resource is intended to be a guide for parents and students to improve content knowledge and understanding in preparation for the cumulative Grade 8 science Standards of Learning test. The information below is detailed information about the Standards of Learning taught in grade 8 physical science and comes from the Science Standards of Learning Curriculum Frameworks, issued by the Virginia Department of Education. The Curriculum Frameworks in their entirety can be found at the following website. http://www.doe.virginia.gov/VDOE/Instruction/Science/ScienceCF-PS.pdf
PS.3
The student will investigate and understand the modern and historical models of atomic structure. Key concepts include a) the contributions of Dalton, Thomson, Rutherford, and Bohr in understanding the atom; and b) the modern model of atomic structure.
The critical scientific concepts developed in this standard include the following:
Many scientists have contributed to our understanding of atomic structure.
The atom is the basic building block of matter and consists of subatomic particles (proton, neutron, electron, and quark) that differ in their location, charge, and relative mass. Protons and neutrons are made up of smaller particles called quarks.
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A proton is a subatomic particle with a positive electric charge. A neutron is a subatomic particle that does not have an electric charge. An electron is a subatomic particle with a negative electric charge. Protons and neutrons are found together in the center, or nucleus, of an atom. Electrons are found orbiting the nucleus. The overall charge of an atom is determined by the number of positively charged protons and negatively charged electrons. If the number of protons is equal to the number of electrons, the positive and negative charges are balanced making the atom stable/neutral. If the number of protons exceeds the number of electrons or the number of electrons exceeds the number of protons, the positive and negative charges are unbalanced making the atom unstable.
Size at the atomic level is measured on the nanoscale.
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Scientists use models to help explain the structure of the atom. Their understanding of the structure of the atom continues to evolve. Two models commonly used are the Bohr and the “electron cloud” (Quantum Mechanics) models. The Bohr model does not depict the three-dimensional aspect of an atom, and it implies that electrons are in static orbits. The “electron cloud” model better represents our current understanding of the structure of the atom.
Dalton’s Model Matter is made of atoms that cannot be created or destroyed. Atoms that are exactly alike form an element. Atoms join with other atoms to form new substances. Thomson’s Model A positive material with negatively charged particles throughout the positive material. Rutherford’s Model A positively charged nucleus surrounded by empty space in which electrons travel around the nucleus.
Bohr’s Model A positively charged nucleus with definite paths/levels/shells in which electrons travel around the nucleus.
Electron Cloud A positively charged nucleus with regions around the nucleus in which electrons travel.
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Released Test Items from the Virginia Standards of Learning, Grade 8 Physical Science Test Answers are located on the last page of the booklet. PS.3, Historical Models/Atomic Structure Spring 2004
Spring 2009 24 How is the modern model of an atom different from the Bohr atomic
model? F The masses of the atomic particles are different. G The numbers of electrons are different. H The shapes of the nuclei are different. J The arrangements of the electrons are different.
34 A student makes a drawing of a carbon atom. Which of these should the
student show in the nucleus of the atom? F Ions G Protons H Electrons J Molecules
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PS.4
The student will investigate and understand the organization and use of the periodic table of elements to obtain information. Key concepts include a) symbols, atomic number, atomic mass, chemical families (groups), and periods; b) classification of elements as metals, metalloids, and nonmetals; and c) formation of compounds through ionic and covalent bonding.
The critical scientific concepts developed in this standard include the following:
There are more than 110 known elements. No element with an atomic number greater than 92 is found naturally in measurable quantities on Earth. The remaining elements are artificially produced in a laboratory setting. Elements combine in many ways to produce compounds that make up all other substances on Earth.
The periodic table of elements is a tool used to organize information about the elements. Each box in the periodic table contains information about the structure of an element.
An atom’s identity is directly related to the number of protons in its nucleus. This is the basis for the arrangement of atoms on the periodic table of elements.
The vertical columns in the table are called groups or families. The horizontal rows are called periods.
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Elements in the same column (family) of the periodic table contain the same number of electrons in their outer energy levels. This gives rise to their similar properties and is the basis of periodicity — the repetitive pattern of properties such as boiling point across periods on the table.
The periodic table of elements is an arrangement of elements according to atomic number and properties. The information can be used to predict chemical reactivity. The boxes for all of the elements are arranged in increasing order of atomic number. The elements have an increasing nonmetallic character as one reads from left to right across the table. Along the stair-step line are the metalloids, which have properties of both metals and nonmetals.
The nonmetals are located to the right of the stair-step line on the periodic table.
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Families or Groups of the Periodic Table Family or Group 1:
Consists of the nonmetal hydrogen and the alkali metals Hydrogen is a reactive gas that reacts explosively with water and has 1 electron in its outermost energy level Alkali metals: 1. Have 1 electron in their outermost energy level 2. Are very reactive 3. Are soft 4. Are silver-colored 5. Have luster 6. Have low density Family or Group 2 is the alkaline-earth metals. Alkaline-earth metals: Have 2 electrons in their outermost energy level Are very reactive, but not as active as alkali metals Silver-colored More dense than alkali metals Family or Groups 3-12 are the transition metals. Transition metals: Have 1 or 2 electrons in their outermost energy level Are less reactive than alkali and alkaline-earth metals Have luster Are good conductors of thermal energy and electric current Have higher melting points and densities than alkali and alkaline-earth metals, except for mercury Family or Group 13 is the boron group. The boron group:
Consists of metals and metalloids Has 3 electrons in their outermost energy level Is reactive Is a solid at room temperature Family or Group 14 is the carbon group. The carbon group: Consists of metals, nonmetals, and metalloids Has 4 electrons in their outermost energy level Is a solid at room temperature Family or Group 15 is the nitrogen group. The nitrogen group:
Consists of metals, nonmetals, and metalloids Has 5 electrons in their outermost energy level Is a solid at room temperature
Consists of metals, nonmetals, and metalloids Has 6 electrons in their outermost energy level Is reactive Is a solid at room temperature, except for oxygen
Family or Group 16 is the oxygen group. The oxygen group:
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Family or Group 17 is the halogens. Halogens:
Consist of nonmetals Have 7 electrons in their outermost energy level Are very reactive Are poor conductors of electric current React violently with alkali metals to form salts
Consist of nonmetals Have 8 electrons in their outermost energy level, except for helium which has 2 electrons in its outermost energy level Are not reactive (unreactive) Are colorless gases Are odorless gases Are gases at room temperature
Family or Group 18 is the noble or inert gases. Noble or inert gases:
Metals tend to lose electrons in chemical reactions, forming positive ions. Nonmetals tend to gain electrons in chemical reactions, forming negative ions.
Gaining or losing electrons makes an atom an ion.
Gaining or losing neutrons makes an atom an isotope. However, gaining or losing a proton makes an atom into a completely different element.
Atoms react to form chemically stable substances that are held together by chemical bonds and are represented by chemical formulas. To become chemically stable, atoms gain, lose, or share electrons.
Compounds are formed when elements react chemically. When a metallic element reacts with a nonmetallic element, their atoms gain and lose electrons respectively, forming ionic bonds. Generally, when two nonmetals react, atoms share electrons, forming covalent (molecular) bonds. Non-metal Element + Non-metal Element = Covalent Bond Metal Element + Metal Element= Ionic Bond
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Released Test Items from the Virginia Standards of Learning, Grade 8 Physical Science Test Answers are located on the last page of the booklet.
PS.4, Organization of The Periodic Table
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Released Test Items from the Virginia Standards of Learning, Grade 8 Physical Science Test Answers are located on the last page of the booklet. PS.4, Organization of The Periodic Table
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Released Test Items from the Virginia Standards of Learning, Grade 8 Physical Science Test Answers are located on the last page of the booklet. PS.4, Organization of The Periodic Table
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PS.5 The student will investigate and understand changes in matter and the relationship of these changes to the Law of Conservation of Matter and Energy. Key concepts include b) chemical changes; Another type of change occurs in nuclear reactions. Nuclear energy is the energy stored in the nucleus of an atom. This energy can be released by joining nuclei together (fusion) or by splitting nuclei (fission), resulting in the conversion of minute amounts of matter into energy. In nuclear reactions, a small amount of matter produces a large amount of energy. However, there are potential negative effects of using nuclear energy, including radioactive nuclear waste storage and disposal. A nuclear reaction is a change involving the nucleus of an atom. The nucleus stores great amounts of energy, called nuclear energy. There are two types of nuclear reactions: Nuclear Fission- a large nucleus of an atom splits into two or more smaller nuclei, releasing energy. ** Remember “fission” means to separate.
In some regions, humans also depend on nuclear fission. Nuclear power plants use this type of reaction to produce electricity. The energy released during nuclear reactions is used to heat water. The steam that is then produced is used to turn a turbine attached to an electric generator.
Advantages of Fission
Disadvantages of Fission
Producing great amount of energy.
Health problems due to radioactive waste that is produced.
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Nuclear Fusion-two small nuclei are joined together to produce a large nucleus and energy. ** Remember “fusion” means to join together.
*Humans depend on nuclear fusion every day because this is the type of reaction occurs in the Sun. The energy released during this nuclear reaction in the Sun reaches the Earth as heat and light.
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Testing Information The 2nd Nine Weeks Test will consist of items from standards PS.1, PS.3, PS.4, PS.5b (included in this booklet), as well as from standard PS.2, which was taught during the 1st Nine Weeks. Refer to the 1st Nine Weeks Content Review Notes to review this content prior to the 2nd Nine Weeks Test.
The 2nd Nine Weeks Test will be given the week of January 21, 2013. Check with your child’s teacher for the specific testing date.
The following pages contain vocabulary sorts that can be used to review for this grading period.
Cut out the sort and practice matching the vocabulary word with the matching description.
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SOL PS.3
atom
The smallest particle into which an element can be divided and still be the same substance.
proton
The positively charged particle of the nucleus
neutron
The particles of the that have no charge
electron
The negatively charged particles found in all atoms
quantum mechanics
A theory of the mechanics of atoms, molecules, and other physical systems that are subject to the uncertainty principle
electron cloud
The regions inside an atom where electrons are likely to be found
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SOL PS.4
periodic table of elements
A table of elements arranged by atomic number that shows patterns in their properties
periods
a row of elements on the periodic table
ion
Charged particles that form during chemical changes
isotope
Atoms that have the same number of protons but have different numbers of neutrons
metals
Elements that are shiny and good conductors of heat and electricity
nonmetals
Elements that are dull and poor conductors of heat and electricity
compound
A pure substance composed of two or more elements that are chemically combined
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SOL PS.4 (continued)
atomic number
The number of protons in the nucleus of an atom
atomic mass
The weighted average of the masses of all the naturally occurring isotopes of an element
ionic bond
The force of attraction between oppositely charged ions
covalent bond
The force of attraction between the nuclei of atoms and the electrons shared by the atoms
metalloids
Elements that have properties of both metals and nonmetals
element
A pure substance that cannot separated or broken down into simpler substances by physical or chemical means
valence electrons
The electrons in the outermost energy level of an atom
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SOL PS.4 (continued)
family
A column of elements on the periodic table
SOL PS.5
fusion
The process by which multiple atomic particles join together to form a heavier nucleus.
fission
The process where a large atomic nucleus splits into two smaller nuclei.
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Released Test Answers (2nd Nine Weeks) SOL PS.3 (Atomic Structure)
SOL PS.4 (Periodic Table)
Spring 2004
Spring 2001
34. H
3. A
36. H
16. J
Spring 2009
34. H
24. J
Spring 2002
34. G
5. C 11. B
Spring 2003 36. H
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