Chapter 2: Chemistry Comes Alive Flashcards
Matter
Anything that occupies space and has mass
Energy
The capacity to do work, or to put matter in motion
Kinetic Energy
Energy in action
Potential Energy
Stored energy
What is the connection between matter and energy?
They are inseparable; Matter is substance and energy is the mover of the substance
Chemical Energy
The form stored in the bonds of chemical substances
1) Atoms rearrange
2) PE is released
3) KE
Describe Eating
1) Food E is captured temporarily in the bonds of a chemical called ATP
2) ATP bonds are broken, PE is released for cellular work
Electrical Energy
Results from the movement of charged particles
- Electrical currents (ions move across cell membranes)
- Nerve impulses
- Pumping blood
Mechanical Energy
Energy directly moving matter
Radiant Energy/ Electromagnetic Radiation
Energy that travels in waves
Electromagnetic Spectrum
Waves that are varied in length
Energy Conversions
- Energy can easily convert
- Inefficient: Initial energy is always “lost” in the environment as heat (unusable energy)
- All conversions give off heat: helps with homeostasis
Elements
Unique substances that cannot be broken down into simpler substances by ordinary chemical means
Atoms
Identical particles or building blocks of elements
Physical Properties
Those we can detect with our senses or measure
Chemical Properties
Pertain to the way atoms interact with other atoms
Nucleus
(1) Control center of a cell; contains genetic material; (2) center of an atom; contains protons and neutrons
Protons
Positive electrical charge
Neutron
Neutral, so nucleus is positive overall
What are the connections between protons, neutrons and the nucleus
1) Protons and neutrons are heavy subatomic particles of the nucleus
2) Nucleus is dense= 99.99% mass of the atom
Electrons
Negative charge equal in strength to the positive charge of the proton
What are all atoms charged?
Neutral; the # of protons in an atom is balanced by its # of electrons
Planetary Model
A simplified model of atomic structure
Orbital
Regions around the nucleus in which a given electron or electron pair is likely to be found most of the time
Orbital Model
More useful for predicting the chemical behavior of atoms
- predicts probable regions of greatest electron density by denser shading (electron cloud)
Atomic number
Equal to the # of protons (electrons)
Mass number
The sum of the masses of its protons and neutrons
Isotopes
2 or more structural variations of elements that have the same # of protons and electrons but a different # of neutrons
Atomic Weights
An average of the relative weights of all the isotopes of an element
- Atomic # = Mass # of most abundant isotope
Radioactivity
The process of atomic decaying spontaneously into more stable forms because of unstable heavier isotopes
Radioisotopes
Isotopes that exhibit radioactivity
Quarks
Smaller particles of the nucleus that associate one way to form protons and another neutrons
- holds nuclear particles together and is weaker in heavier isotopes
Molecule
A combination of 2 or more atoms of the same element held together by chemical bonds
Compound
2 or more different kinds of atoms bind, they form molecules of a compound
- Chemically Pure
- Identical Molecules
Mixtures
Substances composed of 2 or more components physically intermixed
What are the 3 basic types of mixtures?
1) Solutions
2) Colloids
3) Suspension
Solutions
Homogeneous mixtures of components that may be gases, liquids or solids
- Particles are very tiny
- Do not settle
- Scatter light
Solvent
The substance in the greatest amount (or dissolving medium)
- Usually liquid
Solute
Substances present in smaller amounts (dissolved in the solvent)
True Solutions
Contains gases, liquids or solids dissolved in water
- Usually transparent
- Ex: Saline Solution, Mix: Glucose/ Water, and Mineral Water
- Solutes are minute
- Do not settle out/ scatter light
How do you describe True Solutions?
By their concentration
- College/ Hospital: percent (parts per 100 parts) of the solute in the total solution (water is the assumed solvent)
- Blood Concentration: Milligrams per deciliter
- Molarity
Molarity
Moles per liter, M
- Complicated but useful
Mole
Equal to any element or compounds atomic weight or molecular weight
Molecular weight
Sum of atomic weights
Avogadro’s Number
6.02 X 10(23)
Colloids/ Emulsions
Heterogeneous mixtures
- Translucent/ Milky
- Large particles
- Scatter light
- Do not settle
Sol-gel Transformation
To change reversibly from a fluid (sol) state to a more solid (gel) state
- Ex: Jell-O
• Underlie important cell activities
Suspensions
Heterogeneous mixtures
- Very large particles
- Often visible solutes that settle out
- Ex: Blood
What are the differences between mixtures and compounds?
1) No chemical bonding in mixtures (only physically intermixed)
2) Mixtures can be separated by physical means
Compounds—> Chemical means
3) Mixtures: Homogeneous/ Heterogeneous
Compounds: Homogeneous
Chemical Bonds
An energy relationship between the electrons of the reacting atoms
Electron Shells
The regions of space of an atom around the nucleus where electrons are forming an electron cloud
Valence Shell
An atoms outermost energy level containing the electrons that are chemically reactive
What are the 3 major types of chemical bonds?
1) Ionic
2) Covalent
3) Hydrogen
Ions
Charged particles that form when the balance of + and - are lost
Ionic Bond
A Chemical bond between atoms formed by the transfer of one or more electrons from one atom to another
Electron Acceptor
The atom that gains one or more electrons
Anion
The negative net charge in an electron acceptor
Electron Donor
The atom that loses its electrons