General Chemistry Review Topics

A measurement is a

quantitative observation consisting of a number and scale (unit)

A digit that must be estimated is called

uncertain

A measurement always has some degree of

uncertainty

What refers to the agreement of a particular value with the true value?

Accuracy

What refers to the degree of agreement among several measurements made in the same manner?

Precision

Measurement had an equal probability of being high or low.

Random Error

Occurs in the same direction each time, often resulting from poor technique or incorrect calibration.

Systematic Error

All matter is composed of extremely small particles called

atoms

Atoms of a given element are identical in

size, mass, and other properties

Atoms cannot be subdivided, created, or

destroyed

Atoms of different elements combine in simple whole-number ratios

to form chemical compounds

In chemical reactions, atoms are combined,

separated, or rearranged

Dalton said atoms of a given element are identical in size, mass, and other properties;

atoms of different elements differ in size, mass, and other properties

Modern theory states atoms of an element have a

characteristic average mass which is unique to that element

Modern theory states atoms cannot be subdivided, created, or destroyed in

ordinary chemical reactions. However, these changes CAN occur in nuclear reactions

Cathode ray tubes pass electricity through

a gas that is contained at a very low pressure

Robert Millikan determines the mass of the electron which is

9.109×10^-31 kg

Cathode ray have identical properties

regardless of the element used to produce them. All elements must contain identically charged electrons

Atoms are neutral, so there must be positive particles in the atom to

balance the negative charge of the electrons

Electrons have so little mass that atoms must

contain other particles that account for most of the mass

Most of the mass of the atom is in the

nucleus (protons and neutrons)

Most of the volume of the atom is

empty space

Protons and neutrons art NOT

fundamental particles

Isotopes are atoms of the same element having

different masses due to varying numbers of neutrons

Atomic masses the average of all the

naturally occurring isotopes of that element.

Mass number is the number of

protons and neutrons in the nucleus of an isotope.

Two or more atoms of the same or different elements

covalently bonded together.

molecules are discrete structures, and their formulas

represent each atom present in the molecule.

Covalent network substances have covalently bonded atoms, but

do not have discrete formulas.

ionic bonding is

force of attraction between oppositely charged ions

Ionic compounds form crystals so

their formulas are written empirically