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

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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

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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

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