Unit: Atomic Structure

This set of flashcards covers key concepts and vocabulary from the lecture notes on atomic structure.

Atom

The smallest unit of an element, made up of protons, neutrons, and electrons.

Democritus

Greek philosopher who first proposed the existence of atoms around 400 B.C.

Dalton's Atomic Theory

A theory proposing that all matter is made of atoms, which are indivisible and distinct for each element.

Indivisible

Unable to be divided into smaller parts; refers to the original concept of atoms.

Postulate

A statement that is assumed to be true; Dalton had four major postulates in his atomic theory.

Chemical Reaction

A process in which atoms rearrange, separate, or combine to form new substances.

Cathode-Ray Tube Experiment

An experiment conducted by J.J. Thomson that led to the discovery of the electron.

Electron

A subatomic particle with a negative charge, found in the electron cloud surrounding the nucleus.

Plum Pudding Model

J.J. Thomson's model of the atom, suggesting it consists of a positively charged sphere with electrons embedded in it.

Gold Foil Experiment

Rutherford's experiment that led to the discovery of the nucleus of the atom.

Nucleus

The positively charged center of an atom, containing protons and neutrons.

Alpha Particle

A type of particle consisting of two protons and two neutrons, used in Rutherford's experiment.

Proton

A positively charged subatomic particle found in the nucleus of an atom.

Neutron

A neutral subatomic particle found in the nucleus of an atom, with approximately the same mass as a proton.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Subatomic Particle

Particles that make up an atom, including protons, neutrons, and electrons.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a charge.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Valence Electrons

Electrons located in the outermost shell of an atom, responsible for its reactivity.

Bohr Model

A model of the atom that depicts electrons orbiting the nucleus in distinct energy levels.

Electron Cloud Model

A model of the atom proposed by Schrodinger, depicting electrons as existing in probability clouds around the nucleus.

Hydrogen

The simplest and most abundant element, with one proton and one electron.

Neon

A noble gas with ten protons and ten electrons, known for its lack of reactivity.

Alkali Metals

Group 1 elements that are highly reactive and have one electron in their outermost orbital.

Alkaline Earth Metals

Group 2 elements that are reactive and have two electrons in their outermost orbital.

Transition Metals

Elements found in groups 3-12 that have variable oxidation states and are known for their strength and conductivity.

Cation Example

Na+1 represents the sodium cation.

Anion Example

O-2 represents the oxide anion.

Lewis Structure

A diagram that represents the valence electrons of an atom as dots around the atomic symbol.

Group

A column in the periodic table; elements in the same group often have similar chemical properties.

Period

A row in the periodic table; elements in the same period have the same number of electron shells.

Reactive Nonmetals

Elements like halogens that readily gain electrons to form compounds.

Noble Gases

Group 18 elements that are generally unreactive due to having full outermost electron shells.

Metalloids

Elements that have properties of both metals and nonmetals, found along the zigzag line on the periodic table.

Poor Metals

Metals that are not as strong as other metals and exhibit lower melting points.

Rare Earth Metals

A set of 17 metallic elements that are found in small quantities and have unique properties.

Octet Rule

The principle that atoms tend to bond in such a way that they each have eight electrons in their outermost shell.

Energy Level

The specific region around the nucleus where electrons can exist.

Electron Configuration

The arrangement of electrons in an atom, described by energy levels and sublevels.

Ionic Charge

A numeric value representing the number of electrons gained or lost by an atom.

Reactive Metals

Metals that tend to lose electrons and readily react with other elements.

Malleable

The property of metals that allows them to be hammered or pressed into shapes without breaking.

Dull and Brittle

Common characteristics of nonmetals, indicating they do not shine like metals and can break easily.

Chemical Properties

Characteristics of a substance that become apparent during a chemical reaction.

Periodic Table

A chart that organizes all known elements according to their properties and atomic structure.

Mass Number

The total number of protons and neutrons in an atom's nucleus.

Atomic Number

The number of protons in an atom, which determines the element's identity.

Inert Gas

A gas that does not undergo chemical reactions under a set of given conditions.