Atomic Structure and Properties

Greek philosopher who proposed the idea of atoms, theorizing they are indivisible particles.

Greek philosopher who proposed the four elements (earth, air, fire, and water) as the fundamental building blocks of matter.

Tiny particles that make up all matter.

English scientist who discovered the electron, a negatively charged particle found within atoms.

English scientist who proposed the atomic model that suggested atoms have a dense, positively charged nucleus with electrons orbiting around it.

British scientist who discovered the neutron, a neutral particle found within the atom.

The theory stating that matter cannot be created or destroyed, only rearranged.

Scientific model that depicts atoms as having a central, positively charged nucleus with negatively charged electrons orbiting around it.

A substance made up of only one type of atom.

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

The central part of an atom, containing protons and neutrons.

Negatively charged particles that orbit the nucleus of an atom.

Atoms have equal numbers of protons and electrons, making them electrically neutral.

Experiments where alpha particles were fired at a thin sheet of gold foil, revealing the structure of the atom.

Electrons can jump between different energy levels (orbits) around the nucleus.

When electrons drop to a lower energy level, they release energy in the form of light.

Elements in the same vertical column of the periodic table.

Elements in the same horizontal row of the periodic table.

The number of protons in an atom's nucleus.

Electrons in the outermost shell of an atom.

Elements that are shiny, malleable, ductile, and good conductors of heat and electricity.

Elements that have properties of both metals and nonmetals.

Elements that are generally poor conductors of heat and electricity, and often exist as gases.

Elements that are unreactive and found in nature as single atoms.

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

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

A representation of an atom's structure, showing the arrangement of protons, neutrons, and electrons.

A model by Niels Bohr that depicts electrons orbiting the nucleus in specific energy levels or shells.

A model by Ernest Rutherford that describes a central nucleus with positively charged protons and neutrons, surrounded by negatively charged electrons.

Diagrams used to visually represent the arrangement of protons, neutrons, and electrons in an atom.

The average mass of an element's atoms, taking into account the different isotopes.

A diagram showing the arrangement of valence electrons around an atom's symbol.

Elements that have the same number of valence electrons and share similar chemical properties.

Elements that have the same number of electron shells (energy levels) and similar physical properties.

A pure substance made up of only one type of atom. It cannot be broken down into simpler substances by chemical or physical means.

A short symbol used to represent a chemical element. It's typically one or two letters from the element's name.

A pure substance made up of two or more elements chemically combined in a fixed ratio. It has different properties than the individual elements that make it up.

A mixture of two or more substances that are not chemically combined. The components retain their individual properties and can be separated by physical means.

Groups of elements that share similar chemical properties. They are organized in vertical columns on the periodic table.