Chemistry Summary The particle theory: 1. Matter is made of tiny particles 2. Particles of matter are in constant motion 3. Particles of matter are held together by very strong electric forces 4. There are empty spaces between the particles of matter that are very large compared to the particles themselves. 5. Each substance has unique particles that are different from the particles of other substances 6. Temperature affects the speed of the particles. The
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Biology Midterm Review Chapter 2- The Chemical Basis of Life 1: Atoms - The smallest functional units of matter that form all chemical substances - Cannot be further broken down into other substances by ordinary chemical or physical means - Each specific type of atom is a chemical element Three Subatomic Particles: - Protons – Positive (+1)‚ found in nucleus‚ same number as electrons - Neutrons – Neutral (0)‚ found in nucleus‚ number can vary - Electrons – Negative (-1)‚ found
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whose system he later on developed further. Democritus visualized atoms; atom is a Greek word for indivisible‚ which means as moving through space‚ then colliding to form the universe and the natural objects in it. Democritus was said to have excelled in all the branches of knowledge. “His name was associated with the first exposition of the atomic theory of matter‚ according to which all matter is composed of single‚ indivisible atoms exactly alike qualitatively.” (Greek: pg 1) His theory
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Structures 29 Use with Chapter 8‚ Section 8.3 1. Step 1 in drawing the Lewis structure for a molecule is to decide which atoms of the molecule are most likely the terminal ones. In the transparency‚ why are the hydrogen (H) atoms in hydrazine (N2H4) shown as the terminal atoms? 2. Step 2 in drawing a Lewis structure involves determining the total number of valence electrons in the atoms in the molecule. Explain why the total number of valence electrons in N2H4 is 14. 3. Step 3 in drawing a Lewis
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Theory Building models of molecules are useful for visualizing how atoms are connected in three-dimensional space called molecular geometry‚ which is best predicted by Valence-Shell Electron-Pair Repulsion (VSPER) theory. The following are the sets of rules summarizing thsi theory: ● Consider molecules and ions where two or more atoms are bonded to a central atom. ● The electron pairs in the valence shell of the central atom are assumed to position as far apart as possible because electron pair
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from a neutral atom. The IE increase from bottom to top and left to right in the periodic table. (The Shodor Education Foundation‚ Inc. 2000) The IE and atomic radius increase in opposite directions. This makes sense because as the atom gets smaller‚
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of all the atoms present in one molecule of that compound. Example: the molecular mass of sodium bromide‚ NaBr‚ is 103‚ which represents the sum of the atomic mass of sodium (23) plus that of bromide (80). * Calculating the Molecular Mass (Formula Mass) of a Compound * To find the molecular mass of a compound‚ add the atomic masses of all the atoms that are present in that compound. * In the compound H2O‚ the molecular mass can be calculated by adding the mass of two atoms of hydrogen
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BIO 101 – HUMAN BIOLOGY Midterm Exam I – Fall 2007 Please fill in your name and (SOLAR) ID number on your answer sheet before starting. Do not write anything under the column marked birthdate!!!!! Keep the opscan sheet that came with your test and do not use ANY other opscan form or you risk a misgrading. Answers to the multiple choice questions must be filled in on the answer sheet with a #2 pencil. There are 40 multiple choice questions. Answer sheets will be collected when time is called at 8:10
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formed by the joining of two or more atoms. A stable compound occurs when the total energy of the combination has lower energy than the separated atoms. The bound state implies a net attractive force between the atoms ... a chemical bond. The two extreme cases of chemical bonds are: Covalent bond: bond in which one or more pairs of electrons are shared by two atoms. Ionic bond: bond in which one or more electrons from one atom are removed and attached to another atom‚ resulting in positive and negative
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flows in an aqueous solution of ionic compounds‚ the metal ions appears at the negative electrode (cathode). - The metal exists in the solution as positively charged particles known as ions. - A 1+ ion plus one unit of electricity gives one metal atom. - Low pressures gases conduct electricity very well. - The glass of containing vessel opposite the cathode (negatives electrode) glowed when the applied potential difference (voltage) was sufficiently high. - Solid objects cast shadows between
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