Molecules i àtoms

Classified in Chemistry

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• Four observations that suggest a chemical reaction is taking place are the evolution of energy as heat and light, the production of gas, a change in color, and the formation of a precipitate. 
• A balanced chemical equation represents, with symbols and formulas, the identities and relative amounts of reactants and products in a chemical reaction.
The kinetic-molecular theory of matter can be used to explain the properties of gases, liquids, and solids. 
• The kinetic-molecular theory of gases describes a model of an ideal gas. 
• Gases consist of large numbers of tiny, fast-moving particles that are far apart relative to their size.
A crystal structure is the total three-dimensional array of points that describes the arrangement of the particles of a crystal. 
• Unlike crystalline solids, amorphous solids do not have a highly ordered structure or a regular shape.

molar enthalpy of fusion:

the amount of energy as heat required to melt one mole of solid at the solid's melting point
equilibrium: a dynamic condition in which two opposing changes occur at equal rates in a closed system
equilibrium vapor pressure:the pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature
• Gay-Lussac’s law of combining volumes states that the volumes of reacting gases and their products at the same temperature and pressure can be expressed as ratios of whole numbers. 
• Avogadro’s law states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

• Dalton’s law of partial pressures states that in a mixture of unreacting gases, the total pressure equals the sum of the partial pressures of each gas.
• Graham’s law of effusion states that the relative rates of effusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses.
• Acids have a sour taste and react with active metals. Acids change the colors of acid-base indicators, react with bases to produce salts and water, and conduct electricity in aqueous solutions. 
• Bases have a bitter taste, feel slippery to the skin in dilute aqueous solutions, change the colors of acid-base indicators, react with acids to produce salts and water, and conduct electricity in aqueous solution
• An Arrhenius acid contains hydrogen and ionizes in aqueous solution to form hydrogen ions. An Arrhenius base produces hydroxide ions in aqueous solution.
• A Brønsted-Lowry acid is a proton donor. A Brønsted-Lowry base is a proton acceptor. 
• A Lewis acid is an electron-pair acceptor. A Lewis base is an electron-pair donor. 
• Acids are described as monoprotic, diprotic, or triprotic depending on whether they can donate one, two, or three protons per molecule, respectively, in aqueous solutions. Polyprotic acids include both diprotic and triprotic acids.
• In every Brønsted-Lowry acid-base reaction, there are two conjugate acid-base pairs. 
• A strong acid has a weak conjugate base; a strong base has a weak conjugate acid. 
• Proton-transfer reactions favor the production of the weaker acid and weaker base.
• A neutralization reaction produces water and an ionic compound called a salt.
• The pH of a solution can be measured using either a pH meter or acid-base indicators. 
• Titration uses a solution of known concentration to determine the concentration of a solution of unknown concentration. 
• The ability of carbon to bond to other elements and to allow different arrangements of atoms contributes to the diversity of carbon compounds. 
• Isomers are compounds that have the same molecular formula but different structures. In structural isomers, the atoms are bonded together in different orders. In geometric isomers, the order of atom bonding is the same, but the atoms are oriented differently in space.
• Alkanes are saturated hydrocarbons; they contain only single bonds. Physical trends in alkanes correspond to trends in alkane size and amount of branching.
 • Organic compounds are named according to a systematic method.
 • Unsaturated hydrocarbons have one or more multiple carboncarbon bonds: these include alkenes, alkynes, and aromatic hydrocarbons.
• Functional groups are responsible for the properties of the organic compound that contains the functional group
• Alcohols contain the hydroxyl functional group. 
• Alkyl halides contain one or more halogen atoms. 
• Two alkyl groups are joined to an oxygen atom in ethers.
 • Both aldehydes and ketones contain the carbonyl group. 
• Amines are derivatives of ammonia. 
• Carboxylic acids contain carboxyl groups. 
• In esters, the hydrogen atom of a carboxylic acid group has been replaced with an alkyl group.
• Polymers are large molecules made of many repeating units called monomers. A copolymer consists of two or more different monomers.
• Carbohydrates are nutrients that are produced by plants and are made up of carbon, oxygen, and hydrogen. 
• Monosaccharides are the simplest carbohydrates. Carbohydrates made of two monosaccharides are called disaccharides, and carbohydrates made of more than two monosaccharides are called polysaccharides. 
• Carbohydrates undergo condensation reactions and hydrolysis reactions. 
• Lipids are a varied group of biochemical molecules that have a high percentage of C and H atoms
• Amino acid molecules are the basic building blocks of proteins. 
• Proteins are biological polymers, each of which has a unique sequence of amino acid monomer molecules. 
• The specific function of a protein is related to the shape of the protein. 
• Side-chain interactions between amino acids result in secondary, tertiary, and quaternary protein structures.
• ATP is a high-energy storage compound that the body uses to store and provide energy for life. 
• The metabolic pathways involve both the conversion of ATP to ADP and the conversion of ADP to ATP. 
• Metabolic pathways are classified as two types: catabolism and anabolism. 
• Catabolism includes reactions in which large molecules are changed into simpler molecules. These reactions release energy. 
• Anabolic processes are energy-consuming pathways by which cells produce the molecules needed for growth and repair.
• Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are nucleic acids, the compounds by which living organisms can reproduce themselves. 
• Nucleic acids are polymers of monomer units called nucleotides. 
• The two strands of the double helix of DNA are complementary to each other, not identical. These strands are held together by hydrogen bonding of the base pairs. 
• RNA is used to produce proteins in the cell.

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