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Quantum-Mechanical Theory of the Atom 150 150 Deborah

Quantum-Mechanical Theory of the Atom

Overview In the earlier discussion of atomic theory as it relates to chemistry, protons and neutrons were described as being within the nuclei of atoms.  Electrons were in orbit around the nuclei, and were given up or added in the process of ionization.  The orbits of electrons are not in fixed, measureable positions, but can…

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Chemistry Review of Solutions 150 150 Deborah

Chemistry Review of Solutions

Overview: Solutions are special types of mixtures that are homogeneous.  The particles in those mixtures are not chemically combined, so they can be separated by physical processes such as evaporation.  Solutions exist in all three states of matter, gases, liquids, and solids. What Are Some Types of Solutions? Any time that gases do not combine…

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Chemistry Review: States of Matter 150 150 Deborah

Chemistry Review: States of Matter

Overview: Matter is anything that has mass and occupies space, whether it is visible or not.  It exists in three separate states, solid, liquid, and gas.  Each state has its own distinct physical properties. What Are Some Types of Matter? Matter consists of many different substances with fixed composition.  Some of those substances are elements…

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Review of Solid Geometry on the SAT and ACT 812 337 School Tutoring

Review of Solid Geometry on the SAT and ACT

Overview:  What Is Solid Geometry? Solid geometry was developed after plane geometry as a way to describe the three-dimensional world and the objects in it.  In the ideal three-dimensional world, objects exist with faces and angles, depth and volume.  Objects are regular, or consist of a combination of regular objects, just as two-dimensional figures can…

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Review of Math Functions on the SAT and ACT 381 351 School Tutoring

Review of Math Functions on the SAT and ACT

Overview:  What Are Functions? Functions in mathematics describe two different types of relationships between numbers.  The simplest definitions are that a function can be either the set of ordered pairs in which the first element is paired with a second element or the relationship between two sets of elements in which every element in Set…

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Earth’s Oldest Fossils: Stromatolites 150 150 Deborah

Earth’s Oldest Fossils: Stromatolites

Overview: The oldest fossils found on Earth are not dinosaur bones or the insect creatures known as trilobites.  They are one-celled organisms that left ancient deposits over 3.5 billion years ago.  Some forms of those one-celled organisms still exist today, and are forming similar structures throughout many places in the world. What Are Stromatolites? Stromatolites…

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Biology Review of Viruses 150 150 Deborah

Biology Review of Viruses

Overview: Viruses are very basic organisms that are on the border between living and nonliving things.  When they are dormant, they are similar to crystals.  They are only able to reproduce within a living host cell.  Although they contain protein and nucleic acid, they do not grow or respond to stimuli. What Do Viruses Contain?…

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Math Review of Radical Expressions 150 150 Deborah

Math Review of Radical Expressions

Overview Radical expressions involving square roots have many applications in algebra.  If an equation calls for a variable to be squared, its solution will be a square root.  The principal square root is a positive number. What Are Perfect Squares? Perfect squares have whole numbers as square roots.  For example, √9 equals 3, and √16…

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Review of Chemical Formulas 150 150 Deborah

Review of Chemical Formulas

 Overview: Chemical formulas are abbreviations for chemical compounds.  They contain both the elements in the compound and  the ratio of elements to one another.  They are used as shorthand to describe chemical reactions. How Are the Elements Symbolized? The name of each element in the periodic table is abbreviated so that each element has its…

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Nonstandard English: Negative Sentences 160 128 School Tutoring

Nonstandard English: Negative Sentences

Overview:  Why Double Negatives? Some of the most common examples of nonstandard English occur when negative words and statements are misused.  Negatives as alternatives are contained in the English/grammar tests on both the SAT and the ACT to trap the unwary.  The errors can be compounded because double negatives were once considered standard in English,…

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