Chapter 2 The Chemistry of Life Flashcards
Matter
Anything that has mass and occupies space
Solid, liquid, gas
Chemistry
Study of matter and its interactions
Atoms
smallest unit of matter that retains original properties. made up of:
- Subatomic particles
Subatomic Particles
Protons, Neutrons, Electrons
Protons (p+)
In atomic nucleus
-Positively charged
Neutrons (n0)
In atomic nucleus, slightly larger than protons
-no charge
Electrons (e-)
Outside atomic nucleus
-negatively charged
Atomic Nucleus
Central core of atom
Neutral
Atoms are electrically neutral:
-no charge
- number or protons and electrons are equal.
Electron shells
-regions surrounding atomic nucleus
-where electrons exist
- 3 main electron shells
Some atoms may have more than 3 shells
1st electron shell
Closest to nucleus - 2 electrons
2nd electron shell
8 electrons
3rd electron shell
18 electrons, “satisfied” with 8
Atomic Number
number of protons in atomic nucleus; defines every element
Element
substance that cannot be broken down into simpler substance by chemical means. (on periodic table)
-Total number of protons predicts element
Periodic Table
List elements by increasing atomic numbers
4 Major Elements
Human body is made up of:
1. Hydrogen
2. Oxygen
3. Carbon
4. Nitrogen
5. 7 mineral elements and 13 trace elements
Mass Number
sum of all protons and neutrons in atomic nucleus
-Protons are at the bottom / next to element symbol
-Neutrons are on the top / next to element symbol
Isotopes
Atom with same atomic number (number of protons) but different mass number (number of neutrons)
Radioisotopes
Unstable isotopes. High energy or radiation released by radioactive decay, allows isotope to assume more stable form
Mixtures
Atoms of two or more elements physically intermixed without changing chemical of atoms
1.Suspensions
2. Colloids
3.Solutions
Suspension
Ex: blood in suspension
- Large, unevenly distributed particles
-Will settle out when left undisturbed
Generally a liquid mixed with solid
Colloids
Ex: milk
-Small, evenly distributed particles
-Will not settle out
Solutions
Ex: glucose in water
-extremely small, evenly distributed particles
-will not settle
- Solute
- Solvent
Solute
Substance dissolved
ex: sugar in water
Solvent
Substance that dissolves solute
ex: water
Chemical Bond
-Energy relationship or attractive force between atoms
-Formed when valence electrons of atoms interact
Molecule
formed by chemical bonding between two or more atoms of the same element
Compound
formed when two or more atoms from different elements combine by chemical bonding
-Contain both metal and nonmetal ions
Valence Electrons
Determine how an atom interacts with other atoms
Octet Rule
Atom is most stable when 8 electrons in valence shell
Duet Rule
Atoms with 5 or fewer electrons- atom is most stable when valence electron shell holds 2 electrons
Ionic Bond
(ions) Electrons are transferred from metal atoms to nonmetal atom:
-cations
-anions
Cations
Positively charged ion
-Metal loses one or more electrons
Anion
Negatively charged ion
-Nonmetal gains one or more electrons
Covalent Bonds
Strongest bond. two or more nonmetals share electrons
Electronegativity
Protons attract electrons
-increase from bottom left to upper right of periodic table (Fluorine is the most electronegative element)
Nonpolar Covalent Bonds
Two nonmetals in molecule:
-similar or identical electronegativities
-pull with equal force
Nonpolar molecules occur in 3 situations
-Atoms sharing electrons are same element
-Arrangement of atoms makes one atom unable to pull more strongly than another atom
-Bond between carbon and hydrogen
Polar Covalent Bonds
Two Nonmetals with
-different electronegativities
-share electrons unequally
-form polar molecules
Partially negative
Atom with higher electronegativity pulls shared electrons close to itself
Partially Positive
Atom with lower electronegativity , shared electrons are pulled toward other atom
Dipoles
Polar molecules with partially positive and partially negative ends
Hydrogen Bonds
Responsible for key property of water
- weak attractions between partially positive end of a one dipole and partially negative end of another dipole
Chemical Reaction
-Chemical bond is formed, broken, or rearranged
-Electrons are transferred between two or more atoms
Chemical Equation
- Reactants- starting ingredients, will undergo reaction
- Products- results of chemical reaction
Reversible Reactions
Proceed in either direction; denoted by two arrows in opposite direction
Irreversible Reactions
Proceed from left to right, denoted by single arrow
Energy
Capacity to do work or put matter into motion
- Potential
- Kinetic
Potential Energy
Stored, can be released later to do work
Kinetic Energy
Potential energy has been released or set in motion to perform work
-All atoms have kinetic energy (in constant motion)