Science Notes: Matter, Atomic Structure, Energy, and Earth Systems

Vocabulary flashcards covering atomic structure, atomic theory, periodic trends, energy forms and transfers, chemical reactions, and plate tectonics.

Electrically neutral

The condition of having an equal number of protons (positively charged) and electrons (negatively charged).

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom.

Electron configuration

The arrangement showing the number of electrons in each shell of an atom, starting with the innermost shell; for example, $2, 8, 8, 2$.

Electron shell

The region of space surrounding an atom's nucleus in which electrons circulate.

Matter

Any substance that has mass and takes up space.

Molecule

A unit composed of two or more atoms that are chemically bonded together.

Neutron

A neutrally charged subatomic particle located within the nucleus of an atom.

Nucleus

The central core of an atom that contains protons and neutrons, accounting for the vast majority of the atom's mass.

Proton

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

Subatomic particles

The fundamental particles that make up atoms: protons, neutrons, and electrons.

Valence shell

The outermost electron shell occupied by electrons, located furthest away from the nucleus of an atom.

Isotope

A variant of a chemical element having the same number of protons and electrons (identical atomic number and chemical behaviour) but a different number of neutrons, resulting in a unique atomic mass.

Ion

An atom or molecule with a net electrical charge resulting from an unequal number of protons and electrons.

Anion

An ion carrying a negative electrical charge.

Cation

An ion carrying a positive electrical charge.

Alpha particle

A positively charged particle that is four times larger than a proton.

Cathode ray

A stream of electrons observed passing through a high-vacuum tube.

Spectral line

A distinct dark or bright line appearing within an otherwise continuous or uniform spectrum.

Plum Pudding Model

An atomic model proposed by J.J. Thomson in 1904 describing the atom as a sphere of positive charge (the 'pudding') with embedded negatively charged electrons (the 'plums').

Nuclear model of the atom

The atomic model proposed by Ernest Rutherford in 1910 establishing that atoms are mostly empty space with a tiny, dense, positively charged nucleus at the centre orbited by electrons.

Bohr model

An atomic model proposed by Niels Bohr in 1913 in which electrons travel around the nucleus in orbits of fixed sizes and energy levels, similar to planets orbiting the Sun.

Atomic mass

The average mass of the atoms in a sample of an element, typically measured in atomic mass units (amu).

Atomic number

The total number of protons present in the nucleus of an atom.

Chemical symbol

A one- or two-letter notation used to represent a specific chemical element.

Periodic table

A systematic tabular display of all known chemical elements ordered by their atomic number and chemical symbol.

Group (periodic table)

A vertical column in the periodic table; elements within the same group share identical valence electron counts and similar chemical properties.

Period (periodic table)

A horizontal row in the periodic table; elements in the same period possess the same total number of electron shells.

Valence electron

An electron located in the outermost shell (valence shell) of an atom.

Compound

A pure substance formed from atoms of two or more different elements chemically bonded together in fixed ratios.

Energy

The capacity or ability to do work, exert a force over a distance, or produce change.

Kinetic energy

The form of energy associated with the motion of an object.

Potential energy

Stored energy possessed by an object that has the capacity to cause movement or make things happen.

Work

The process that occurs when a force applied to an object causes that object to move.

Conduction

The transfer of thermal energy between substances in direct physical contact, passing from the hotter object to the cooler one.

Convection

The transfer of thermal energy through the bulk movement of a liquid or gas driven by density differences.

Radiation

The transfer of thermal energy through electromagnetic waves that does not require contact with or propagation through matter.

Closed system

A thermodynamic system that allows energy to transfer across its boundaries but prevents the transfer of matter.

Isolated system

A thermodynamic system that completely prevents the exchange of both matter and energy with its surroundings.

Open system

A thermodynamic system that freely permits both matter and energy to enter and exit.

Conservation of energy

The fundamental scientific law stating that energy cannot be created or destroyed, only transferred or transformed.

Conservation of mass

The fundamental scientific law stating that mass cannot be created or destroyed during a physical or chemical process.

Chemical change

A transformation that alters the chemical properties of substances, resulting in the formation of one or more new substances.

Physical change

A change affecting the appearance, state, or form of a substance without altering its fundamental chemical composition or forming a new substance.

Endothermic reaction

A chemical reaction that absorbs thermal energy from its surroundings.

Exothermic reaction

A chemical reaction that releases thermal energy into its surroundings.

Combustion

The exothermic chemical reaction of a substance with oxygen that produces heat.

Corrosion

The chemical reaction that takes place between a metal and oxygen.

Asthenosphere

The ductile, semi-fluid portion of the upper mantle situated directly beneath the rigid lithosphere.

Lithosphere

The rigid, brittle outer shell of Earth consisting of the crust and uppermost mantle, segmented into tectonic plates.

Subduction

The tectonic process in which the edge of one lithospheric plate moves downward beneath another into the mantle.

Convergent boundary

A tectonic plate boundary where two plates move toward each other and collide.

Divergent boundary

A tectonic plate boundary where two plates move away from each other.

Transform boundary

A tectonic plate boundary where two plates slide horizontally past one another.