Chemistry

True or false? You can only smell substances that are gasses at room temperature.

False. Substances that are liquids and solids have some molecules that escape and become a gas.

Pressure

Force applied over a specific area. Force per unit area.

Percent Error

A calculation used to find the accuracy of a measurement. The lower the percent error, the more accurate the measurement.

Physical Change

A change that alters the form of a substance but does not change the chemical identity of a substance.

Decomposition Reaction

A chemical change in which a single substance is broken down into two or more simpler substances.

Single Exchange Reaction

A chemical change in which an element is displaced from a compound by a more reactive element.

Double Exchange Reaction

A chemical change in which both reactants break apart and then recombine to form two new products; chemical change where there is an exchange of ions between reactants to form new products.

Mole

A counting unit used to keep track of large numbers of particles. One mole represents 6.02 × 1023 items.

Trigonal Planar Shape

A flat triangular shape that is found in small molecules with three electron domains surrounding a central atom.

Intermolecular Force

A force of attraction that occurs between molecules.

Solution

A homogenous mixture of two or more substances.

Air Mass

A large volume of air that has consistent temperature and water content.

Partial Charge

A less than full charge on part of a molecule, created by the unequal sharing of electrons. Partial charges are represented with the symbol delta (δ+ for partial positive charge and δ−for partial negative charge).

Electronegativity

A measure of the ability of an atom in a molecular substance to attract electrons to itself.

Concentration

A measure of the amount of solute dissolved per unit of volume of solution, often expressed as moles of solute per liter of solution, mol/L.

Temperature

A measure of the average kinetic energy of the atoms and molecules in a sample of matter.

Heterogenous Mixture

A mixture whose composition is not uniform throughout.

Homogenous Mixture

A mixture whose composition is uniform throughout.

Diatomic Molecule

A molecule consisting of two atoms.

Dipole

A molecule or covalent bond with a nonsymmetrical distribution of electrical charge that makes the molecule or bond polar.

Polar Molecule

A molecule that has a negatively charged end and a positively charged end due to electronegativity differences between the atoms and/or the asymmetry of its structure.

Nonpolar Molecule

A molecule that is not attracted to an electrical charge. A molecule is nonpolar if each atom shares electrons equally or there is no net dipole in the molecule.

Avogadro's Number

A number equal to 6.02 × 1023. It is the number of particles (atoms, ions, molecules, or formula units) present in one mole of a substance.

Universal Gas Constant, R

A number that relates the volume, temperature, pressure and number of moles of gas in the ideal gas law. The value of R is dependent on the units used. One value of R is 0.08206 L · atm/mol · K.

Combination Reaction

A reaction in which two or more reactants combine to form a single product.

Avogadro's Law

A scientific law stating that equal volumes of gases at the same temperature and pressure contain equal numbers of particles.

Electron Domain Theory

A scientific theory that states that every electron domain is located as far away as possible from every other electron domain in a molecule.

Saturated Solution

A solution that contains the maximum amount of solute that can be dissolved in a given amount of solvent at a particular temperature.

Standard Temperature and Pressure (STP)

A standard set of conditions at which gases can be measured and compared. Standard pressure is 1 atm and standard temperature is 273 K (0 °C).

Linear Shape

A straight- line shape found in small molecules.

Solute

A substance dissolved in a solvent to form a solution.

Solvent

A substance in which another substance is dissolved, forming a solution.

Kelvin Scale

A temperature scale with units in kelvins, K, that sets the zero point at −273.15 ˚C, which is also known as absolute zero. Kelvin units are equivalent in scale to Celsius units.

ball- and- stick model

A three-dimensional representation of a molecule that uses color-coded balls to represent atoms and sticks to represent bonds.

Space-filling model

A three-dimensional representation of a molecule with no space between bonded atoms, as distinct from a ball-and-stick model.

Phase Change

A transition between solid, liquid, or gaseous states of matter.

Atmosphere (atm)

A unit of measurement for gas pressure. One atmosphere is equivalent to 14.7 pounds of pressure per square inch or a barometric reading of 760 millimeters of mercury.

If a molecule is minty, camphor, or sweet-smelling what functional group will it be in?-2

Alcohol function group.

O II - C -OH

Carboxylic acid-putrid

What happens to a substance that has undergone sublimation?

It has a lower density.

If a molecule is fishy-smelling what functional group will it be in?

It's an amine function group.

If a molecule is putrid-smelling what functional group will it be in?

It's an caboxyl function group.

If a molecule is sweet-smelling what functional group will it be in?

It's an ester function group.

If a molecule is minty, camphor, or sweet-smelling what functional group will it be in?-1

It's an ketone function group.

Motor oil does not dissolve easily in water. Why?

Motor oil is nonpolar and water is polar, so the molecules are not attracted to each other.

Atmospheric Pressure

Pressure exerted by the weight, or force, of the air pressing down on a surface. Air pressure is a result of air molecules colliding with the surfaces of objects on Earth. At sea level, atmospheric pressure equals approximately 1 atm or 14.7 lb/in2.

Inversely Proportional

Related in such a way that when one quantity increases, the other decreases in a mathematically predictable way. The variables x and y are inversely proportional to each other if y = k/x, where k is the proportionality constant.

Proportional

Related such that when one quantity increases, the other also increases. Two variables are proportional when you can multiply one variable by a constant to obtain the other. The variable y is proportional to the variable x if y = kx where k is the proportionality constant.

Relative Humidity

The amount of water vapor in the air compared to the maximum amount of water vapor possible for a specific temperature, expressed as a percentage.

What happens in a nonpolar covalent bond?

The bonded electrons are equally shared between the atoms.

Molarity

The concentration of dissolved substances in a solution, expressed in moles of solute per liter of solution.

Humidity

The concentration of the water vapor in the air at any given time.

Receptor Site Theory

The currently accepted model explaining how specific molecules are detected by the nose. Molecules fit into receptor sites that correspond to the overall shape of the molecule. This stimulates a response in the body.

Weather

The day-to-day atmospheric conditions such as temperature, cloudiness, and rainfall, affecting a specific place.

Toxicity

The degree to which a substance can harm an organism. Toxicity depends on the toxin and the dose in which it is received.

Combined Gas Law

The law that describes the proportional relationship among the pressure, temperature, and volume of a gas. It states that the value of PV/T will be constant for a given sample of any gas.

Charle's Law

The law that states that the volume of a given sample of gas is proportional to its Kelvin temperature if the pressure is unchanged.

Molar Mass

The mass in grams of one mole of a substance.

Bent Shape

The nonlinear shape around a bonded atom with two lone pairs of electrons.

Number Density

The number of gas particles per unit volume usually expressed in moles per liter or moles per cubic centimeter.

Proportionality Constant

The number that relates two variables that are proportional to one another. It is often represented by k.

Coefficients

The numbers in front of the chemical formulas of the reactants and products in a balanced chemical equation. They indicate the correct ratio in which the reactants combine to form the products.

Evaporation

The phase change from a liquid to a gas.

Partial Pressure

The pressure exerted by one gas in a mixture of non reacting gases. The partial pressures of all the gases add up to the total pressure exerted by that mixture of gases.

Sublimation

The process of changing phase from a solid to a gas without passing through the liquid phase.

Ideal Gas Law

The scientific law that relates volume, pressure, temperature, and the number of moles of a gas sample: PV = nRT, where R is the universal gas constant.

Gay-Lussac's Law

The scientific law that states that the pressure of a given amount of gas is directly proportional to temperature, if the gas volume does not change.

Boyle's Law

The scientific law that states that the volume of a given sample of gas at a given temperature is inversely proportional to its pressure.

Kinetic Theory of Gasses

The scientific theory that states that gases are composed of tiny particles in continuous, random, straight-line motion and collide with each other and the walls of the container.

Pyramidal Shape

The shape assumed by other bonded atoms around an atom with one lone pair of electrons.

Tetrahedral Shape

The shape defined by the symmetrical distribution of four bonded pairs of electrons around a central atom.

Formula Unit

The simplest chemical formula that can be used to represent network covalent or ionic compounds that shows the elements present in the smallest whole number ratio.

Electron Domain

The space occupied by bonded pairs or lone pairs of valence electrons in a molecule. Electron domains affect the overall shape of a molecule.

Boiling Point

The temperature at which both liquid and gas phases of a single substance are present and in equilibrium; the temperature at which equilibrium is established between a liquid and its vapor at a pressure of 1 atm.

Melting Point

The temperature at which both solid and liquid phases of a single substance can be present and in equilibrium.

Absolute Zero

The temperature defined as 0 K on the Kelvin scale and −273.15 °C on the Celsius scale. Considered to be the lowest possible temperature that matter can reach.

Volume decreases. What happens to the temperature and pressure?

They increase.

Why does the foul smell of butyric acid disappear when you mix it with methanol an heat it up?

a chemical reaction takes place creating a new molecule.

OH I - C - I

alcohol

H H I I -C - C- I I H H

alkane-gasoline

N I - C - I

amine-fishy

What happens in an ionic bond?

an electron (or electrons) is given up to the more electronegative atom.

In a polar covalent bond the elecrtons__

are shared unequally

ball

camphor

What elements are included in the structure of every amine?

carbon, hydrogen, and nitrogen

O II I - C - O - C - I

ester-sweet

-ine

fishy

1 N atom

fishy

You can only smell molecules when they are in what phase?

gas

-ane

gasoline

At what electronegativity difference between atoms is a bond considered polar covalent?

greater than .6 and lower than 2.1

At what electronegativity difference between atoms is a bond considered nonpolar covalent?

greater than 0 and lower than .6

At what electronegativity difference between atoms is a bond considered ionic?

greater than 2.1

O II - C -

ketone-minty

-one

minty

frying pan

minty

-ol

minty, camphor, sweet

1 O atom

minty, camphor, sweet

Why does decreasing the volume of a gas cause the pressure to increase if temperature is constant?

molecules strike the walls of the container more often.

-ic acid

putrid

-ate

sweet

stringy

sweet

2 O's

sweet or putrid

What happens in a polar covalent bond?

the bonded electrons spend more time around the more electronegative atom.

Where are the atoms with the greatest electronegativity values located?

upper right corner of the periodic table