Topic 2: What is our world made of? Flashcards
Matter
Anything that has mass and takes up space
Element
A pure substance that consists entirely of one type of atom and cannot be chemically broken into simpler substances
Atom
The smallest unit of an element that retains its properties
Molecule
The smallest unit of most compounds that displays the properties of that compound
Compound
A substance made up of atoms of two or more different elements joined by chemical bonds
Pure substance
A sample of matter (single element/compound) that has definite chemical and physical properties
Mixture
A material composed of two or more substances that are physically mixed together but not chemically combined
Melting point
The temperature and pressure at which a solid becomes a liquid
Boiling point
The temperature and pressure at which a liquid becomes a gas
Density
The ratio of the mass of a substance to its volume
Reactivity
The capacity of a substance to combine with another
Physical change
A change of matter from one form to another without change in chemical properties
Chemical change
When one or more substances change into entirely new substances with different properties
Evaporation
The change of state from a liquid to a gas
Condensation
The change of state from a gas to a liquid
Sublimation
The process in which a solid changes directly into a gas
Fluid
A non-solid state of matter in which the atoms or molecules are free to move past each other – gas or liquid
Plasma
A state of matter that consists of free-moving ions and electrons
Energy
The capacity to do work. Measured in joules.
Temperature
A measure of the average kinetic energy of the particles of an object
Thermal energy
The total kinetic energy of a substance’s atoms
Pressure
The amount of force exerted per unit area of a surface (F/A)
Pascal
The SI unit of pressure (N/m^2)
Viscosity
The resistance of a gas or liquid to flow
Buoyant force
The upwards force that keeps an object immersed in or floating on a fluid
Electron
A negatively charged particle, located in the space surrounding the nucleus
Nucleus
The center of an atom, which contains the protons and neutrons
Isotope
One of two or more atoms of the same element that have the same number of protons, but different numbers of neutrons
Valence electron
An electron that is found on the outermost shell of an atom and determines its chemical properties
Photon
A particle of electromagnetic radiation that has zero rest mass and carries a quantum of energy
