Chapter 2
Chemistry Comes Alive
2.1 Matter and Energy
• is anything that has mass and occupies space
• Matter can be seen, smelled, and/or felt
• is mass plus the effects of gravity
• States of matter
• Matter can exist in three possible states:
• : definite shape and volume
• : changeable shape; definite volume
• : changeable shape and volume
Energy
• Energy is the capacity to do work or put matter into motion
• Energy does not have mass, nor does it take up space
• The greater the work done, the more energy it uses up
– Energy exists in two possible forms:
• – energy in action
• – stored (inactive) energy
– Energy can be transformed from potential to kinetic energy
• Stored energy can be released, resulting in action
• Forms of energy
:
• Stored in bonds of chemical substances
:
• Results from movement of charged particles
:
• Directly involved in moving matter
:
• Travels in waves (example: heat, visible light, ultraviolet light, and X rays)
2.2 Atoms and Elements
• All matter is composed of .
• Elements are substances that cannot be broken down into simpler substances by ordinary chemical methods
• Four elements make up 96% of body:
• Carbon, oxygen, hydrogen, and nitrogen
• 9 elements make up 3.9% of body
• 11 elements make up <0.01%
• Periodic table lists all known elements
2.2 Atoms and Elements
• All elements are made up of , which are:
• Unique building blocks for each element
• Smallest particles of an element with properties of that element
• What give each element its particular physical & chemical properties
Atoms and Elements (con’t)
• Atomic symbol
• One- or two-letter chemical shorthand for each element
• Example: “O” for oxygen, “C” for carbon
• Some symbols come from Latin names: “Na” (natrium) is sodium; “K” (kalium) is potassium
Structure of Atoms
• Atoms are composed of three subatomic particles:
:
• Carry a positive charge (+)
• Weigh an arbitrary 1 atomic mass unit (1 amu)
:
• Have no electrical charge (0)
, • Also weigh 1 am
:
• Carry a negative charge ()
• Are so tiny they have virtually no weight (0 amu)
• Number of positive protons is balanced by number of negative electrons, so atoms are electrically neutral
• Protons and neutrons are found in a centrally located ; electrons orbit around the nucleus
Identifying Elements
• Different elements contain different numbers of subatomic particles
• Hydrogen has 1 proton, 0 neutrons, and 1 electron
• Helium has 2 protons, 2 neutrons, and 2 electrons
• Lithium has 3 protons, 4 neutrons, and 3 electrons
• Identifying facts about an element include its atomic number, mass number, isotopes, and atomic weight
• :
• Number of protons in nucleus
• Written as subscript to left of atomic symbol
• Example: 3Li
• Mass number
• Total number of protons and neutrons in nucleus
• Total mass of atom
• Isotopes
– Structural variations of same element
– Atoms contain same number of protons but differ in the number of neutrons they contain
• Atomic numbers are same, but mass numbers different
• Atomic weight
• Average of mass numbers of all isotope forms of an atom
2.3 Combining Matter
Molecules and Compounds
• Most atoms chemically combine with other atoms to form molecules and compounds
• : general term for 2 or more atoms bonded together
• : specific molecule that has 2 or more different kinds of atoms bonded together
• Example: C6H12O6
• Molecules with only one type of atom (H2 or O2) are just called molecules
Mixtures
• Most matter exists as mixtures: two or more components that are physically intermixed
• Three basic types of mixtures
• Solutions
o Are mixtures, meaning particles are evenly distributed throughout
o Solvent: substance present in greatest amount
o Usually a liquid, such as water
o Solute(s): substance dissolved in solvent
o Present in smaller amounts
o Example: blood sugar – glucose is solute, and blood (plasma) is solvent
o True solutions are usually transparent
o Example: air (gas solution), salt solution, sugar solution
o Most solutions in body are true solutions of gases, liquids, or solids dissolved in water
• Colloids
o Also known as ; are heterogeneous mixtures, meaning that particles are not evenly
distributed throughout mixture
o Can see large solute particles in solution, but these do not settle out
o Gives solution a cloudy or milky look
o Some undergo sol-gel (solution to gel) transformations
o Example: Jell-O goes from liquid to gel
o Cytosol of cell is also a sol-gel type solution
• Suspensions
o mixtures that contain large, visible solutes that do settle out
o Example: mixture of water and sand
Chemistry Comes Alive
2.1 Matter and Energy
• is anything that has mass and occupies space
• Matter can be seen, smelled, and/or felt
• is mass plus the effects of gravity
• States of matter
• Matter can exist in three possible states:
• : definite shape and volume
• : changeable shape; definite volume
• : changeable shape and volume
Energy
• Energy is the capacity to do work or put matter into motion
• Energy does not have mass, nor does it take up space
• The greater the work done, the more energy it uses up
– Energy exists in two possible forms:
• – energy in action
• – stored (inactive) energy
– Energy can be transformed from potential to kinetic energy
• Stored energy can be released, resulting in action
• Forms of energy
:
• Stored in bonds of chemical substances
:
• Results from movement of charged particles
:
• Directly involved in moving matter
:
• Travels in waves (example: heat, visible light, ultraviolet light, and X rays)
2.2 Atoms and Elements
• All matter is composed of .
• Elements are substances that cannot be broken down into simpler substances by ordinary chemical methods
• Four elements make up 96% of body:
• Carbon, oxygen, hydrogen, and nitrogen
• 9 elements make up 3.9% of body
• 11 elements make up <0.01%
• Periodic table lists all known elements
2.2 Atoms and Elements
• All elements are made up of , which are:
• Unique building blocks for each element
• Smallest particles of an element with properties of that element
• What give each element its particular physical & chemical properties
Atoms and Elements (con’t)
• Atomic symbol
• One- or two-letter chemical shorthand for each element
• Example: “O” for oxygen, “C” for carbon
• Some symbols come from Latin names: “Na” (natrium) is sodium; “K” (kalium) is potassium
Structure of Atoms
• Atoms are composed of three subatomic particles:
:
• Carry a positive charge (+)
• Weigh an arbitrary 1 atomic mass unit (1 amu)
:
• Have no electrical charge (0)
, • Also weigh 1 am
:
• Carry a negative charge ()
• Are so tiny they have virtually no weight (0 amu)
• Number of positive protons is balanced by number of negative electrons, so atoms are electrically neutral
• Protons and neutrons are found in a centrally located ; electrons orbit around the nucleus
Identifying Elements
• Different elements contain different numbers of subatomic particles
• Hydrogen has 1 proton, 0 neutrons, and 1 electron
• Helium has 2 protons, 2 neutrons, and 2 electrons
• Lithium has 3 protons, 4 neutrons, and 3 electrons
• Identifying facts about an element include its atomic number, mass number, isotopes, and atomic weight
• :
• Number of protons in nucleus
• Written as subscript to left of atomic symbol
• Example: 3Li
• Mass number
• Total number of protons and neutrons in nucleus
• Total mass of atom
• Isotopes
– Structural variations of same element
– Atoms contain same number of protons but differ in the number of neutrons they contain
• Atomic numbers are same, but mass numbers different
• Atomic weight
• Average of mass numbers of all isotope forms of an atom
2.3 Combining Matter
Molecules and Compounds
• Most atoms chemically combine with other atoms to form molecules and compounds
• : general term for 2 or more atoms bonded together
• : specific molecule that has 2 or more different kinds of atoms bonded together
• Example: C6H12O6
• Molecules with only one type of atom (H2 or O2) are just called molecules
Mixtures
• Most matter exists as mixtures: two or more components that are physically intermixed
• Three basic types of mixtures
• Solutions
o Are mixtures, meaning particles are evenly distributed throughout
o Solvent: substance present in greatest amount
o Usually a liquid, such as water
o Solute(s): substance dissolved in solvent
o Present in smaller amounts
o Example: blood sugar – glucose is solute, and blood (plasma) is solvent
o True solutions are usually transparent
o Example: air (gas solution), salt solution, sugar solution
o Most solutions in body are true solutions of gases, liquids, or solids dissolved in water
• Colloids
o Also known as ; are heterogeneous mixtures, meaning that particles are not evenly
distributed throughout mixture
o Can see large solute particles in solution, but these do not settle out
o Gives solution a cloudy or milky look
o Some undergo sol-gel (solution to gel) transformations
o Example: Jell-O goes from liquid to gel
o Cytosol of cell is also a sol-gel type solution
• Suspensions
o mixtures that contain large, visible solutes that do settle out
o Example: mixture of water and sand
