Matter Classification & Atomic Theory

Flashcards based on Lecture 4 covering classification of matter, chemical reactions, atomic theory, subatomic particles, isotopes, mass spectrometry, and the periodic table.

Element

The simplest kind of material with unique physical and chemical properties.

Compound

A pure substance consisting of two or more elements linked together in definite proportions in a fixed ratio.

Mixture

A variable combination of two or more pure substances in solid, liquid, or gas state that can be physically separated without chemical reactions.

Homogeneous Mixture

A mixture, also called a solution, in which the constituents are distributed uniformly throughout the sample.

Heterogeneous Mixture

A mixture in which the individual components can be seen as separate domains and the composition is not uniform.

Chemical Reaction

A transformation of one or more substances into different substances that takes place when molecules collide with enough force to break them into atoms.

Chemical Equations

Expressions that use chemical formulas to express the identities and quantities of substances involved in a chemical reaction.

Atomic Theory

A theory stating that atoms are the fundamental structural blocks of substances, with electrons situated at comparatively large distances around the nucleus.

Neutron

An electrically neutral particle with a mass of $1.008665\,amu$ that is unstable outside the nucleus.

Proton

A stable particle with a positive electric charge of $1.6 \times 10^{-19}\,C$ and a mass of $1.007276\,amu$ that may transform to neutrons inside the nucleus.

Atomic Number

The value that uniquely identifies an element, representing the number of protons in an atom.

Isotopes

Different types of atoms (nuclides) of the same element that have different numbers of neutrons, differing in mass number but never in atomic number.

Radioisotopes

Isotopes that undergo radioactive decay.

Mass Spectrometer

An instrument that measures precisely the masses and relative abundances of ions of atoms and molecules using deflection based on $Z/A$.

Periodic Table

A tabular display of chemical elements that provides a framework to classify, systematize, and compare their chemical and physical properties.

Mendeleev's Periodic Table

An early periodic table in which open spaces were left to account for elements that were not yet discovered.

Modern Periodic Table

A classification table of elements ordered in terms of increasing atomic number, reflecting their physical and chemical properties and electronic configuration.

Periods

The horizontal rows in the periodic table.

Groups

The vertical columns in the periodic table containing elements of the same family with similar valence electron configurations and chemical properties.

Main Group Elements

Elements located in groups 1 and 2 (1A and 2A) and groups 13 through 18 (3A through 8A), also known as representative elements.

Transition Metals

Elements located in groups 3 through 12 (or 1B through 10B) of the periodic table.

Halogens

The elements located in group 17 of the periodic table.

Noble Gases

The elements located in group 18 of the periodic table.