Term
| What are the major components of an atom? |
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Definition
| The atomic nucleus, made up of protons and neutrons, which are surrounded by orbiting electrons |
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Term
| Atoms are classified into elements depending on what property of an atom? |
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Definition
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| How can the mass number of an element be used to determine how many neutrons are present in an atom of the element? |
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Definition
| # of neutrons = Mass number - Atomic number |
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Term
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Definition
| any of several forms of an element that have the same number of protons but differ in the number of neutrons |
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Term
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Definition
| a group of orbitals of electrons with similar energies; arranged in roughly concentric layers around the nucleus of an atom, and electrons in outer shells have more energy than those in inner shells; 1st shell can hold 2 electrons; 2nd and 3rd can hold 8 electrons |
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Term
| What property of an atom is the major factor in determining the chemical reactivity of an atom? |
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Definition
| Valence electrons (electrons in the valence shell) |
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Term
| What elements are similar in chemical reactivity to oxygen? Explain. |
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Definition
| Sulfur, because it has the same amount of valence electrons |
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Term
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Definition
| electrons are shared and are very strong |
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Term
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Definition
| electrons are transferred and are usually weak |
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Term
| Explain how ionic bonds form |
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Definition
| Ionic bonds are similar in principle to covalent bonds, but instead of being shared between two atoms, the electrons in ionic bonds are completely transferred from one atom to the other. The electron transfer occurs because it gives the resulting atoms a full outermost shell. |
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Term
| How does a hydrogen bond form? |
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Definition
| When two water molecules approach each other, the partial positive charge on hydrogen attracts the partial negative charge on oxygen. This weak electrical attraction forms a hydrogen bond between the molecules. In an aqueous solution, hydrogen bonds also form between water molecules and other polar molecules. Similar interactions occur between water and ions. Ions and polar molecules stay in solution because of their interactions with water’s partial charges. |
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Term
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Definition
| a measure of the ability of an atom to attract electrons toward itself from an atom to which it is bonded; determines whether the atom forms a polar or nonpolar covalent bond because it will create asymmetric sharing (polar covalent) of electrons are symmetrically sharing (non-polar covalent) |
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Term
| What type of bond is present WITHIN a molecule of water? |
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Definition
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Term
| What type of bond occurs between DIFFERENT water molecules? |
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Definition
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Term
| What types of substances are hydrophilic? |
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Definition
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Term
| What types of substances are hydrophobic? |
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Definition
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Term
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Definition
| In ice, each water molecule participates in four hydrogen bonds. These hydrogen bonds cause the water molecules to form a regular and repeating structure, or crystal. The crystal structure of ice is fairly open, meaning that there is a relatively large amount of space between molecules. In liquid water, the extent of hydrogen bonds in liquid water is much less than that found in ice, and that the hydrogen bonds in liquid water are constantly being formed and broken. As a result, molecules in the liquid phase are packed much more closely together than in the solid phase. |
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Term
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Definition
| attraction between like molecules; happens because of the hydrogen bonds that form between individual molecules |
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Term
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Definition
| attraction between unlike molecules; water adheres to surfaces that have any polar or charged components |
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Term
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Definition
| the cohesive force that causes molecules at the surface of a liquid to stick together; happens because there are no water molecules above them for hydrogen bonding, as a result, they exhibit stronger attractive forces between their nearest neighboring molecules enhancing attraction between the surface water molecules resulting in tension that minimizes the total surface area |
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Term
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Definition
| amount of energy required to raise the temp. of 1 g of a substance by 1 degree C. As molecules increase in overall polarity, and thus in their ability to form hydrogen bonds, it takes an extraordinarily large amount of energy to change their temperature |
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Term
| Acidic (having acidic properties) |
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Definition
| donates [H+] (protons) to solution. [H+] present in solution making it more... |
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Term
| Basic (having basic properties) |
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Definition
| accepts [H+] (protons) to solution. [H+] taken into molecules making it more... |
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Term
| 1st law of Thermodynamics |
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Definition
| Energy is neither created nor destroyed |
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Term
| 2nd law of Thermodynamics |
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Definition
| Universe is continually increasing in entropy (disorder) |
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Term
| The potential energy is highest for an electron orbiting an atom when... |
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Definition
| the electron is in the outermost electrons shells (or furthest away from the nucleus) |
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Term
| Chemical bond energy is also.. |
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Definition
| Stored energy (potential energy) |
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Term
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Definition
| energy is released; results in increase of entropy; spontaneous reactions |
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Term
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Definition
| require input of energy; non-spontaneous reaction |
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Term
| Which of the following occurs when a covalent bond forms? |
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Definition
| Electrons in valence shells are shared between nuclei |
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Term
| What factors determine whether a chemical reaction is spontaneous or not? |
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Definition
| Potential energy and entropy |
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Term
Which of the following molecules would you predict to have the largest number of polar covalent bonds based on their molecular formulas?
a. C2H6O (ethanol)
b. C2H6 (ethane)
c. C2H4O2 (acetic acid
d. C3H8O (propanol) |
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Definition
| C2H4O2 (acetic acid) – Acetic acid has more highly electronegative oxygen atoms than the other molecules. When bonded to carbon or hydrogen, each oxygen will result in a polar covalent bond |
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