Unit 1 Test Review - Vocabulary Flashcards

Vocabulary flashcards covering matter, atoms, properties, formulas, mixtures, and isotopes from Unit 1.

Matter

Anything that has mass and occupies space

Atoms

Building blocks of matter

Elements

Pure substances made of only one type of atom; cannot be broken down into simpler substances by chemical means.

Molecules

Two or more atoms bonded togethe

Compounds

Substances consisting of two or more elements ; can be decomposed by chemical reactions.

States of matter

solid, liquid, and gas

Physical properties

Characteristics observed without changing the substance’s identity (e.g., color, density, melting point).

Chemical properties

Characteristics observed during chemical changes or reactions (e.g., reactivity, flammability).

Intensive properties

Properties that do not depend on amount of substance (e.g., density, boiling point).

Extensive properties

Properties that depend on the amount of substance (e.g., mass, volume).

Accuracy

Proximity of a measurement to the true or accepted value.

Precision

Proximity of several measurements to each other

Significant figures rule 1

• All nonzero digits are significant

Significant figure rule 2

• Zeroes between two significant figures are themselves significant

Significant figure rule 3

• Zeroes at the beginning of a number are never significant

Significant figure rule 4

• Zeroes at the end of a number are significant if a decimal point is written in the number

Significant figure rule 5

• When addition or subtraction is performed, answers are rounded to the least significant decimal place

Significant figure rule 6

• When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation

Dalton’s four postulates

1) All matter is made of atoms; 2) Atoms of a given element are identical; 3) Atoms aren’t created/destroyed in reactions; 4) Atoms combine in simple whole-number ratios to form compounds.

Subatomic particles

Protons and neutrons in the nucleus; electrons in the surrounding electron cloud.

Isotopes

Atoms of the same element with different numbers of neutrons, giving different mass numbers.

Homogeneous mixture

A uniform composition throughout; components are not visibly distinguishable (e.g., saltwater).

Heterogeneous mixture

A nonuniform composition with visually distinguishable components (e.g., fruit salad).

Salt water

A homogeneous mixture of dissolved salt in water.

Sand in water

A heterogeneous mixture where sand is dispersed in water.

Mercury

An element; pure substance consisting of one type of atom (symbol Hg).

Carbon dioxide

A compound with the formula CO2; a molecule composed of one carbon and two oxygens.

Cake batter

A heterogeneous mixture with nonuniform composition.

Fruit salad

A heterogeneous mixture of pieces of fruit.

Tungsten

An element; a metal (symbol W).

Water (H2O)

A compound consisting of two hydrogen atoms and one oxygen atom; molecule H2O.

Empirical formula

The lowest whole-number ratio of elements in a compound.

Molecular formula

The exact number of each type of atom in a molecule; may be the same as or a multiple of the empirical formula.

Average atomic mass

Weighted average mass of an element’s isotopes based on natural abundances.

Isotopes and average mass calculation

To compute average mass, multiply each isotope’s mass by its fractional abundance and sum.