Qualitative Chemistry

Valence Electrons The electrons in an atom’s outermost orbit; determine the chemical properties of an element.

Electron Dot Structure Consist of the atomic symbol and dots which represent the number of electrons in the out most energy level of than element

Octet Rule States that atoms lose, gain, or share electrons in order to acquire a full set of eight valence electrons.

Oxidation Number The superscript which tells the charge of the element and the number of electrons it needs or can give up in order to be stable

Anion A negatively charged ion

Cation A positively charged ion

Monatomic Ion An ion formed from only one atom

Polyatomic Ion An ion made up of two or more atoms bonded together that acts as a single unit with a net charge.

Coefficient Is the number found in front of an ion or compound. It tells the number of that ion or compound you have

Types of chemical bonds Ionic Bonds Covalent Bonds Metallic Bonds

Bonding Pair Pair of valence electrons which bond two atoms together.

Lone Pair Pair of valence electrons which are not bonded to another element.

Unpaired Electron A valence electron that is not partnered with another electron.

Double Bond Where two elements are bonded together by two pairs of valence electrons. (4 electrons)

Triple Bond Where two elements are bonded together by three pairs of valence electrons. (6 electrons)

Physical Reaction When a substance changes physically but the substance stays the same.

Chemical Reaction When a substance goes through a reaction and changes into another substance.

Signs of Chemical Change Change of color Release of gas Release of energy Release of heat Absorption of heat Release of light

Intensive Property A physical property that remains the same no matter how much of a substance is present.

Extensive Property A physical property, such as mass, length, and volume, that is dependent upon the amount of substance present.

Qualitative Data Information describing color, odor, shape, or some other physical characteristic.

Quantitative Data Numerical information describing how much, how little, how big, how tall, how fast, etc.

Mixture When more than one compound is mixed together to form a substance. The compounds can physically be separated.

Heterogeneous Mixture One that does not have a uniform composition and in which the individual substances remain distinct

Homogeneous Mixture One that has a uniform composition throughout and always has a single phase; also called a solution.

Solute A substance that is dissolved by another substance. There is less of it.

Solvent A substance that dissolves another substance. There is more of it.

Unsaturated Solution A solution that is able to dissolve additional solute.

Saturated Solution A solution that cannot dissolve any more solute under the given conditions.

Supersaturated Solution refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances.

Phase Changes Solid Liquid Gas Plasma

Solid The phase where the particles are held very close together and hold a definite shape.

Liquid The phase where the particles are held close together and do not hold a definite shape. Usually takes the shape of the container.

Gas The phase where the particles are held near each other and has no definite shape

Plasma A state of matter where particles have been reduced to its most basic form. Usually found in stars

As a substance is heated, the particles move more, this causes the substance to expand. When cooled, the substance contracts. The exception to this is water, which expands when cooled and heated.

Ways Matter Change Melting Freezing Evaporation Vaporization Condensation Sublimation Solid to liquid Liquid to solid Liquid to gas Gas to liquid Solid to gas

Melting Point The exact temperature at which a solid changes into a liquid

Boiling Point The exact temperature at which a liquid changes into a gas

Heating Curve for Water 120 °C steam 100 °C water  steam 50°C liquid water 0 °C ice  liquid -10 °C ice Heat added 

Viscosity A fluid’s resistance to flow

Accuracy and Precision

Precision Is the degree of exactness to which the measurement of a quantity can be reproduced

Accuracy Is the extent to which a measured value agrees with the standard value of a quantity.

Precision and Accuracy