Physical Science - Chapter 2

Matter

2A: Composition of Matter

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

What is matter made of?

  • 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

2B: Classifying Matter

Why bother with classifying matter?

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

How do we classify matter?

  • 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

2C States of Matter

What are the states of matter?

  • ==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

2D: Changes in State

What are physical properties?

  • ==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

What are chemical properties?

  • ==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

Is it possible to get rid of matter? Or make more?

NO!!

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

What does it mean for matter to “change states”?

  • ==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