Physical Science - Chapter 2

2A: Composition of Matter

==Matter==: anything that occupies space and has mass
- light, sound, and volume are @@NOT@@ matter

Ancient Thoughts
- “Atomists” thought that matter was made of indivisible atoms and nothing existed between them
- Aristotle, believed that matter consisted of a continuum that could be infinitely cut without changing the characteristics of that matter
- Over time, the @@law of definite proportions@@, @@Brownian motion@@, and the concept of @@diffusion@@ all gave evidence for a @@particle model of matter@@
==Law of Definite Proportions==: the law that states that the masses of chemical substances combine in definite, characteristic integer ratios when forming compounds
==Particle Model of Matter==: a model that states that all physical matter exists in the form of particles (atoms or molecules) in constant motion
- also called the @@kinetic model@@
==Atom==: the building block of all matter, consisting of ==protons==, ==electrons==, and (usually) ==neutrons==
==Molecule==: a distinct group of two or more ==covalently bonded== together

classification systems provide a structure within which we can conduct a scientific study
classification enables us to do science

we classify matter based on its properties
==Pure substance==: a material made of only one kind of element or compound; not a mixture
- a pure substance may be either an @@element@@ or a @@compound@@
- ==Element==: a pure substance that consists of atoms with the same ==atomic number==
- elements are the simplest of the pure substances
==Compound==: a pure substance consisting of atoms of two or more different elements that are chemically combined
- atoms of a particular compound always combine in the same proportion
==Mixture==: a physical combination of two or more substances (elements, compounds, or other mixtures) in a changeable ratio
- a mixture may be either @@heterogeneous@@ or @@homogeneous@@
- @@Heterogeneous mixture@@: a mixture that does not have uniform appearances since the combined are unevenly distributed
- @@Homogeneous mixture@@: a mixture that has a uniform appearance throughout
- a homogeneous mixture is also known as a solution

==Solid==: the state of matter in which particles vibrate in fixed positions, giving a substance a fixed shaped and volume
- Particle spacing: close
- Particle motion: vibrating in space
- Volume: fixed
- Shape: fixed
- Compressibility: low
- Density: high
- Fluid? no
==Liquid==: the state of matter in which particles are close together but able to move around
- Particle spacing: close
- Particle motion: able to slide past each other
- Volume: fixed
- Shape: changes to fill a container from the bottom
- Compressibility: low
- Density: between that of a solid and that of a gas
Fluid? yes
@@Viscosity@@: the attractive forces between the liquid particles determine the viscosity of a liquid (resistance to flowing)
==Gas==: the state of matter in which particles are far apart, move rapidly, and have little interaction with each other
- Particle spacing: widely spread
- Particle motion: high speed
- Volume: changes to fill the container
- Shape: changes to fill the container
- Compressibility: high
- Density: low
- Fluid? yes
- @@Pressure@@: due to collisions with container surface
==Plasma==: a gas-like state of matter, formed at very high temperatures, that consists of high-energy ions and free electrons

==Physical Properties==: anything a substance that can be observed or measures without altering the substance’s chemical composition
- @@Ductility@@: the ability of a solid material to be pulled into a wire
- @@Malleability@@: the ability of some solid materials to be hammered or pressed into sheets
- @@Conductivity@@: the ease with which a material allows the transfer of either electrical or thermal energy
- @@Luster@@: the quality of how a material reflects lights
==Physical Changes==: any change in matter that does not alter the composition of the substance

==Chemical Properties==: a property of a substance that describes how its chemical identity changes in the presence of another substance or under certain conditions
- @@Reactivity@@: the degree to which a material will react with other substances
- @@Flammability@@: the ability of a material to burn in the presence of oxygen
==Chemical Changes==: changes that alter the chemical composition of a substance

NO!!

==Law of Conservation==: a fundamental natural law that states that matter can neither be created nor destroyed but can only ==change forms==

==Melting==: the change of state from solid to a liquid
==Melting point==: the temperature at which a solid turns to a liquid
==Freezing==: the change of state from a liquid to a solid
- the freezing point is the same temperature as the melting point
==Vaporization==: the change of state from a liquid to a vapor (gas)
- vaporization can occur in two ways: @@evaporation@@ and @@boiling@@
==Evaporation==: the relatively slow form of vaporization in which liquid particles obtain sufficient energy to change to the gaseous state through the random collisions of particles
==Boiling==: the relatively fast form of vaporization in which the energy within a liquid creates higher pressure within the liquid than the air pressure outside the liquid
- boiling point: the temperature at which a liquid starts to boil
- the boiling point changes as air pressure changes
==Condensation==: the change of state from a vapor to a liquid
==Sublimation==: the change in state directly from a solid to a gas (vapor) without melting first
==Deposition==: the change in state directly from a gas (vapor) to a solid without condensing first