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| basic unit of matter that contains subatomic particles even smaller. study of chemistry begins with the atom. has a neutral charge bcuz they have equal numbers of protons and electrons (equal but opposite charges cancel out) |
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| subatomic particles that make up atoms |
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- positively charged
- same mass as neutron
- part of nucleus
- same number of electrons and protons in an atom |
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- neutral (no) charge
- same mass as protons
- part of nucleus
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- negative charge
- 1/1840 the mass of a proton
- attached to positively charged nucleus but remain outside of nucleus bcuz of the energy of their motion
- same number of protons as electrons in atom |
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| STRONG forces bind protons and neutrons together to form the nucleus which is at the center of the atom |
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| a chemical element is a pure substance that consists entirely of one type of atom. represented by one or two letter symbol (C = carbon and Na = sodium) |
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| number of protons in an atom of an element is the elements atomic number |
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atoms of the same elements that differ in the number of neutrons they contain are known as isotopes (identified by mass number)
because they have the same number of electrons, all isotopes of an element have the same chemical properties |
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| sum of the protons and neutrons in the nucleus of an atom |
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isotopes with an unstable nuclei that breaks down at a constant rate over time
can be used:
- to determine the ages of rocks and fossils
- treat cancer
- kill bacteria
- as labels or "tracers" to follow movement of substances within an organism |
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| a substance formed by the chemical combination of two or more elements in definite proportions (physical and chemical properties of a compound are diff from elements from which it formed) |
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| atoms in compounds are held together by a chemical bond. 2 types: ionic and covalent |
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| an ionic bond is formed when one or more electrons are transfered from one atom to another. an atom that loses electrons is positive and atom that gains electrons is negative (positive and negative charged atoms are ions) |
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| forms when electrons are shared between atoms. when atoms share two electrons, the bond is called a single covalent bond |
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| smallest unit of most compounds |
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| when molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules |
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| a water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. because of their partial positive and partial negative charges, polar molecules can attract eachother. |
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| not as strong as ionic or covalent bonds but water's ability to form multiple hydrogen bonds is responsible for many of water's properties |
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| an attraction between molecules of the same substance |
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| attraction between molecules of different substances |
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| one of the forces that draw water out of the roots of a plant and up into its stem and leaves against the force of gravity |
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| a material composed of two or more elements or compounds that are physically mixed together but not chemically combined. 2 types of water mixtures: solutions and suspensions |
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| all the components of a solution are evenly distributed through out the solution |
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| substance that is dissolved |
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| substance in which the solute dissolves |
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| the movement of water molecules keeps the small particles suspended. such mixtures of water and nondissolved material are known as suspensions. some materials do not dissolve when placed in water but separate into tiny pieces that do not settle out |
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| a measurement system devised by chemists to indicate the concentration of H+ ions in solution. ranges from 0 to 14 (7 is neutral) |
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| any compound that forms H+ ions in a solution . contain higher concentrations of H+ ions than pure water and have pH values below 7. dangerous substance. |
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| a compound that produces hydroxide ions (OH- ions) in solution. contain lower concentrations of H+ ions than pure water and have pH values of above 7. dangerous substance. |
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| weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. keep human body pH value between 6.5 and 7.5 |
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| 4 groups of organic compounds found in living things |
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1. carbohydrates
2. lipids
3. nucleic acid
4. proteins |
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| formed by a process known as polymerization in which small units called monomers join together to form polymers |
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| compounds made up of carbon, hydrogen, and oxygen atoms. living things use carbohydrates as their main source for energy. plants and some animals also use carbohydrates for structural purposes. (ex: starch and sugar) |
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| single sugar molecules (glucose, galactose, and fructose) |
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| large macromolecules formed from monosaccharides (glycogen or animal starch, and plant starch) |
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| made mostly from carbon and hydrogen atoms (fats, oils, steroids,and waxes). lipids can be used to store energy. some are important parts of biological membranes and waterproof coverings. |
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| macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus. nucleic acids are polymers assembled from individual monomers known as nucleotides. nucleic acids store and transmit hereidtary or genetic info. |
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consist of 3 parts: a 5-carbon sugar, a phosphate group, and a nitrogenous base. can be joined by covalent bonds to form a polynucleotide. |
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1. ribonucleic acid (RNA) which contains sugar ribose
2. deoxyribonucleic acid (DNA) which contains sugar deoxyribose |
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| macromolecules that contain nitrogen, carbon, hydrogen, and oxygen. proteins are polymers of molecules called amino acids. |
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| compounds with an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end |
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1. some proteins control the rate of reactions and regulate cell processes
2. some are used to form bones and muscles
3. transport substances into or out of cells
4. help fight disease |
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| 4 levels of protein organization |
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1. amino acids have a specific protein chain
2. the amino acids within a chain can be twisted or folded
3. the chain itself is folded
4. if a protein has more than one chain, each chain has a specific arrangement in space |
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| process that changes one set of chemicals into another set of chemicals. involve changes in chemical bonds that join atoms in compounds. |
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| elements or compounds that enter in to a chemical reaction |
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| elements or compounds produced by a chemical reaction |
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| chemical reactions that release energy often occur spontaneously. chemical reactions that absorb energy will not occur without a source of energy. |
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| chemists call the energy that is needed to get a reaction started the activation energy |
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| a substance that speeds up the rate of a chemical reaction. they work by lowering a reaction's activation energy. |
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| proteins that act as biological catalysts. enzymes speed up chemical reactions that take place in cells. they act by lowering activation energy. |
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