Chapter 2 - Nature of Molecules; Props of H20 Flashcards Preview

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Flashcards in Chapter 2 - Nature of Molecules; Props of H20 Deck (52):
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Atomic Mass

# of protons and neutrons

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Atomic number

# of protons in nucleus- determines chemical

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Mass

Amount of a substance

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Element

Any substance that cannot be broken down to any other substance by ordinary chemical means

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Dalton

Mass of atoms and subatomic particles is measured in daltons

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Neutral atom

Have same numbers of protons and electrons

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Ion

Charged particle that is formed when an atom gains or loses an electron

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Cation

Atom having more protons than electrons; has a net positive charge

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Anion

Atom with fewer protons than electrons; carries negative net charge

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Isotope

Atoms of a single element that possess different #s of neutrons

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Oxidation

Loss of electron by atom or molecule; in metabolism, often associated with a gain of oxygen or loss of hydrogen.

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Reduction

Electron(s) passed from one atom to another

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Redox reaction

One species is reduced another oxidized

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Valence electron

Can participate in the formation of a chemical bond

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Octet rule

The octet rule is a chemical rule of thumb that states that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

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Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon.

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Molecule

A molecule /ˈmɒlɪkjuːl/ is an electrically neutral group of two or more atoms held together by chemical bonds.

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Chemical compound

a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions.

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Ionic bond

a type of chemical bond that involves the electrostatic attraction between oppositely charged ions. These ions represent atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as an anion). In simpler words, an ionic bond is the transfer of electrons from a metal to a non-metal in order for both atoms to obtain a full valence shell.

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Chemical bond

attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electrostatic force of attraction between opposite charges between electrons and nuclei

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Covalent bond

A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.

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Hydrogen bond

A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge.

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Van der waals attraction

A weak attractive force between atoms or nonpolar molecules caused by a temporary change in dipole moment arising from a brief shift of orbital electrons to one side of one atom or molecule, creating a similar shift in adjacent atoms or molecules.

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Ionic compound

chemical compound in which ions are held together by ionic bonds.

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Single covalent bond

A single bond is when two electrons--one pair of electrons--are shared between two atoms. It is depicted by a single line between the two atoms. Although this form of bond is weaker and has a smaller density than a double bond and a triple bond, it is the most stable because it has a lower level of reactivity meaning less vulnerability in losing electrons to atoms that want to steal electrons.

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Double covalent bond

A Double bond is when two atoms share two pairs of electrons with each other. It is depicted by two horizontal lines between two atoms in a molecule. This type of bond is much stronger than a single bond, but less stable; this is due to its greater amount of reactivity compared to a single bond.

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Structural formula

Eg: h-h, o=o

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Molecular formula

H2, O2

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electronegativity

Affinity for electrons. Force atoms used to try to pull electron from another atom (attracted negatives and positives). They "share" by this "tug of war."

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Nonpolar covalent bond

Electrons (+/-) equally shared, resulting in non-polar molecules

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Polar covalent bond

Electrons are unequally shared and sharing is so unequal it results in polar molecules (more of a charge in one part than another)

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Nonpolar molecule

A molecule may be nonpolar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule.

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Polar molecule

A polar molecule has a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically. Water (H2O) is an example of a polar molecule since it has a slight positive charge on one side and a slight negative charge on the other.

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Chemical reaction

Formation and breaking of chemical bonds. All involve shifting of atoms from one molecule or ionic compound or another, without change in # or identity of atoms

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Reactants & products

A+B -> C+D

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Catalyst

Substance that increases rate of reaction

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Cohesion

Molecules sticking together

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Adhesion

H20 molecules tend to stick to charged surfaces

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Surface tension

Result of cohesion

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Buffer

Substance that resists changes in pH. Act by releasing H+s when a base is added and absorbing H+s when acid is added, with effect of keeping H+ relatively constant

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Base

Combines with H+ when dissolved in H20, and thus lowers H+. Raises pH. pH value above 7.

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Acid

Dissociates in H20 to increase H+ (decreasing pH).

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pH scale

Used to measure relative strength of acidic and basic solutions

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Hydration shell

Sucrose molecule dissociates, or breaks away, from a solid sugar crystal, H20 molecules surround it in a cloud, forming H she'll that prevents it from associating with sucrose molecules

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Hydrophobic exclusion

Tendency of Nonpolar molecules to aggregate in H20

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Mole

Defined as weight of substance in grams that corresponds to atomic masses of all of the atoms in a molecule of that substance

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Hydrogen ion

hydrogen ion, strictly, the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton. The isolated hydrogen ion, represented by the symbol H +, is therefore customarily used to represent a proton.

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Hydroxide ion

The hydroxide ion is a negatively charged molecule made up of one oxygen bonded to one hydrogen. When dissolved in water, the hydroxide ion is an incredibly strong base. In fact, according to the Arrhenius definition of a base, the presence of a hydroxide ion is what makes a chemical a base.

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Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls.

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Functional group

In organic chemistry, functional groups are specific groups of atoms or bonds within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of.

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Hydroxyl group

The hydroxyl group is a pair of atoms that is commonly found in organic compounds such as sugars and alcohols. Learn more about the importance of this group and quiz yourself at the end.

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Carbonyl group

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound.