Intro Chem Unit 1

Atom

the fundamental building block of all matter, the smallest unit of a chemical element that retains its properties, composed of a nucleus (proton & neutrons) surrounded by electrons.

Molecule

the smallest unit of a substance that keeps its chemical properties, formed by two or more atoms joined by chemical bonds. EX: O2 or H2O

Chemistry

the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules.

Hypothesis

a tentative interpretation or explanation of the observations. It can be falsifiable (refuted or confirmed by further observations).

Experiments

highly controlled procedures designed to generate observations that confirm or refute a hypothesis.

Scientific law

a brief statement that summarizes past observations and predicts future ones. describe how nature behaves — they are generalizations about what nature does.

law of conservation of mass

In a chemical reaction, matter is neither created or destroyed.

Scientific theory

a model for the way nature is and tries to explain not merely what nature does but way.

Atomic theory

proposes that all matter is made of tiny particles called atoms

Matter

anything that occupies space and has mass

Substance

a specific instance of matter

crystalline

a solid where atoms are arranged in a highly ordered, repeating 3 dimensional pattern (crystal lattice)

Pure substance

matter with a fixed composition and uniform properties throughout, meaning it’s made only of one type of atom

Mixture

a physical combination of two or more components in proportions that can vary from one sample to another.

Element

pure substance made of only one type of atom, defined by a specific number of protons. An element cannot be chemically broken down into simpler substances

Compound

a substance composed of 2 or more elements in a fixed, definite proportion.

Decanting

a separation technique to pour off a liquid from a solid sediment, relying on density differences after letting components settle.

Distillation

a separation technique that purifies liquids or separates components from a liquid mixture by exploiting differences in their boiling points

Filtration

a physical separation technique used to separate solid particles from a liquid or gas by passing the mixture through a porous filter medium that traps the solids while allowing the fluid to pass through.