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Ch 2


Matter anything that takes up space and has mass
Atoms the smallest chemical units of matter
Element a substance that cannot be broken down into another substance by ordinary chemical means An element is composed of atoms
Electrons negatively charged subatomic particles circling a nucleus
Neutrons uncharged particles
Protons positively charged particles
Nucleus structure containing neutrons and protons
Atomic Number equal to the number of protons in the nucleus It is also equal to the number of electrons And protons if it is not an isotope
Atomic Mass sum of masses of protons, neutrons, and electrons Electrons are have very little mass
Element composed of a single type of atom
Compound composed of atoms of different elements; two or more atoms held together by chemical bonds * All compounds are molecules, but not all molecules are compounds *H2O - Compound *N2- Molecule
Isotopes Atoms of a given element can differ in the number of neutrons in their nuclei - Stable isotopes - Unstable isotopes
Radioactive isotopes Release energy during radioactive decay
Valence electrons electrons in outermost shell that interact with other atoms; combining capacity of an atom pos - gives up electron neg - empty spaces stable - 8 in outer shell
Molecule two or more atoms held together by chemical bonds
Chemical Bonds atoms combine by sharing or transferring valence electrons
Electronegativity attraction of atom for electrons * The more electronegative an atom, the greater the pull its nucleus exerts on electrons.
Covalent share electrons to complete valence shell - Nonpolar covalent: equal sharing - Polar covalent: not equal sharing
Ionic attraction between opposite charges; Gives up or accepts electrons; Atoms have either + (cation) or - e (anion) charges; Cations n anions attract each other n form ionic bonds (no electrons shared); Typically form crystalline ionic compounds aka salts
Valence Bond combining capacity of an atom pos - gives up electron neg - empty spaces stable - 8 in outer shell
Complete Valence Nonpolar - equal sharing Polar- no equal sharing
Nonpolar Covalent Bonds * Shared electrons spend equal amounts of time around each nucleus. - Atoms with similar electronegativities * Carbon atoms form four nonpolar covalent bonds with other atoms. - Organic compounds contain carbon and hydrogen atoms.
Polar Covalent Bonds * Unequal sharing of electrons due to significantly different electronegativities * Most important polar covalent bonds involve hydrogen. - Allow for hydrogen bonding
Hydrogen Bonds *Think H2O * Electrical attraction between partially charged H+ and full or partial negative charge on same or different molecule * Weaker than covalent bonds but essential for life * Help to stabilize 3-D shapes of large molecules
Synthesis Reactions * Involve the formation of larger, more complex molecules * Require energy (endothermic) * Common type is dehydration synthesis * Water molecule formed
Anabolism All the synthesis reactions in an organism
Decomposition Reactions * Break bonds within larger molecules to form smaller atoms, ions, and molecules * Release energy (exothermic) * Common type is hydrolysis * Ionic components of water are added to products (H+, OH-).
Catabolism All the decomposition reactions in an organism C6H12O6 + 6 O2 → 6 H2O + 6 CO2
Exchange Reactions * Involve breaking and forming covalent bonds * Have endothermic and exothermic steps * Involve atoms moving from one molecule to another
Metabolism Sum of all chemical reactions in an organism A + BC → AB + C
Water Most abundant 2 polar covalent bonds: Cohesion & adhesion Excellent solvent Remains liquid across wide range of temps Can absorb sig amounts of heat energy wo changing temp Participates in many chemical reactions Density
Acid * dissociates into one or more H+ and one or more anions ; 0-6.9 *HCl : H+ Cl- : Acidic
Base *binds with H+ when dissolved in water; some dissociate into cations and OH– ; 7.1 - 14 NaOh : Na+ OH- : Base
Buffers Keep pH from changing; prevent drastic changes in internal pH
Living things pH is 6.5 - 8.5
Salts Compounds that dissociate in water into cations n anions other than H+ / OH– Cations/anions of salts r electrolytes that: Create electrical diff between inside/ outside of cell Transfer electrons frm 1 location to another
Functional Groups Atoms often appear in arrangements
Macromolecules * large molecules used by all organisms: 1. Lipids 2. Carbohydrates 3. Proteins 4. Nucleic acids * small building blocks that all stick together to make bigger things
Monomers basic building blocks of macromolecules
Polymers monomers joined together in chains
Lipids * Not composed of regular subunits * Are all hydrophobic * Four groups: 1. Fats (triglycerides) 2. Phospholipids 3. Waxes 4. Steroids * Waxes Contain one long Lack hydrophilic head Completely insoluble in water
Carbohydrates Organic molecules composed of carbon, hydrogen, and oxygen Funct: Lterm storage of chemical energy Part of backbones of nucleic acids Converted to amino acids Form cell wall Involved in intracellular interactions between animal cells
Types of Carbohydrates Monosaccharides * come together to make polymers Disaccharides Polysaccharides
Proteins Composed mostly of carbon, hydrogen, oxygen, nitrogen, and sulfur Functions: Structure Enzymatic catalysis Regulation Transportation Defense and offense
Amino Acids * monomers that make up proteins *Most organisms use only 21 amino acids in protein synthesis. * Side groups affect how amino acids interact with one another n how a protein interacts w other molecules. * covalent peptide bond is formed between a.a.
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) the vital genetic material of cells and viruses.
RNA acts as enzyme, binds amino acids, and helps form polypeptides.
Nucleotides * Monomers that make up nucleic acids Composed of three parts: 1. Phosphate 2. Pentose sugar—either deoxyribose or ribose 3. One of five cyclic nitrogenous bases
Nucleic Acid * DNA is genetic material of all organisms and of many viruses. * Carries instructions for synthesis of RNA and proteins * Controls synthesis of all molecules in an organism * DNA is double stranded in most cells and viruses.
Adenosine triphosphate (ATP) Energy currency of cells Cells use ATP to carry out activities. One nucleotide along with 3 phosphate groups makes it unstable. Easily loses a phosphate group to become ADP (adenosine diphosphate) Continual cycle of breakdown and regeneration
Which of the following structures have no electrical charge? A. Protons B. Electrons C. Neutrons D. Ions Neutrons
The atomic mass of an atom most closely approximates the sum of the masses o all its: A. protons B. isotopes C. electrons D. protons and neutrons protons and neutrons
One isotope of iodine differs from another in: A. the number of protons B. the number of electrons C. the number of neutrons D. atomic number the number of neutrons
Which of the following is NOT an organic compound? A. monosaccharide B. formaldehyde C. water D. Steroid Water
Which of the following terms most correctly describes the bonds in a molecule of water? A. nonpolar covalent bond B. polar covalent bond C. ionic bond D. hydrogen bond Polar Covalent Bond
In water, cations and anions of salts dissociate crom one another and become surrounded by water molecules. In this state, the ions are also called ______________. A. electrically negative B. Ionically bonded C. Electrolytes D. Hydrogen bonds Electrolytes
Which of the following can be most accurately described as a decomposition reaction? A. C6H12O6 + 6 O2 ---> 6 H2O + 6 CO2 B. glucose + ATP ---> glucose phosphate + ADP C. 6 H2O + 6 CO2 ---> C6H12O6 + 6 O2 D. A + BC ---> AB + C C6H12O6 + 6 O2 ---> 6 H2O + 6 CO2
Which of the following statements about a cola beverage w a pH is true? A. relatively high concentration of hydrogen ions B. relatively low concentration of hydrogen ions C. equal amounts of hydroxyl and hydrogen ions D. Cola is a buffered solution relatively high concentration of hydrogen ions
Proteins are polymers of ________. A. amino acids B. fatty acids C. nucleic acids D. monosaccharides Amino Acids
Which of the following are hydrophobic organic molecules? A. proteins B. carbohydrates C. lipids D. nucleic acids Lipids
Th outermost electron shell of an atom is known as the ____________ shell. Valence
The type of chemical bond between atoms with nearly equal electronegativities is call a(n) _______________________ bond. Nonpolar covalent bonds
The principal short-term energy storage molecule in cells is ____________________. ATP
Common long-term storage molecules are: fat, wax, amylase (starch), gylocogen
Groups of atoms such as NH2 or OG that appear in certain common arrangements are called ______________. functional groups
The reverse of dehydration synthesis is ________________. Hydrolosis
Reactions that release energy are called _____________ reactions. exothermic
All chemical reactions begin with reactants and result in new molecules called _____________. products
The ________________ scale is a measure of the concentration of hydrogen ions in a solution. pH
A nucleic acid containing the base uracil would also contain ____________ sugar. Ribose
Created by: Cpvander
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