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| organisms are composed of ___, which is anything that takes up space and has mass |
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| anything that takes up space and has mass |
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| ___ is made up of elements |
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| is a substance that cannont be broken down to other substances by chemical reactions |
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__ is a substance consisting of two or more different elements combined in a fix ration |
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what is this example of: pure sodium is a metal and pure chlorine is a poisonous gas. When combined chemically sodium and chloride form an edible compound. |
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| examples of organized matter having emergent properties |
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| __ is a compound that has characteristics different from those of its elements |
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| identify the 4 elements that make up 96% of living matter? |
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| carbon, oxygen, hydrogen and nitrogen |
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| what other elements make up 4% of an organisms weight? |
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| phosphorous, sulfur, calcium and potassium |
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| are those required by an organism in only minute quantities. |
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| what is this an example of: in vertebrates, the element iodine is an essential ingredient of a hormone produced by the thyroid gland. A daily intake of only 0.15miligrams of iodine is adequate for normal activity of the human thyroid. An iodine deficiency in the diet can cause thyroid to grow to abnormal size |
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| each element consists of a certain kind of _ that is different from the atoms of any other element |
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| is the smallest unit of matter that still retains the properties of an element |
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| although an atom is the smallest unit having the properties of its elements, these tiny bits of matter are composed of even smaller parts called |
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| what three kinds of particles are relevent in an atom |
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| neutrons, protrons and electrons |
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| _ and _ are electrically charged |
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| each _ has one unit of positive charge |
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| each _ has one unit of negative ceharg |
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| what make up the atomic nucleus? |
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| __ form a cloud of negative charge around the nucleus |
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| what keep the electrons in the vicinity of the nucleus? |
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| attraction between opposite charges. |
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| the nuetron and proton are almost identical in mass,each about 1.7x10-24g.grams and other conventional units are not useful for describing the mas of objects so miniscule. Thus for atoms and subatomic particles, __ is used |
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| the number of protons is called ( and located bottom left of the symbol) |
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| __tells the number of protons and electrons |
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| number of nuetrons can be found from |
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| sum of protons and neutrons |
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_____the atom’s total mass, can be approximated by the mass number. |
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The __ is the sum of the number of protons and neutrons in the nucleus of an atom.Therefore, we can determine the number of neutrons in an atom by subtracting the number of protons (the atomic number) from the mass number.
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__of an atom, a measure of its mass, can be approximated by the mass number. For example, 4He has a mass number of 4 and an estimated __ of 4 daltons. |
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two atoms of the same element that differ in the number of neutrons are called |
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Most isotopes are __; they do not tend to loose particles.Both 12C and 13C are__ isotopes. |
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The nuclei of some isotopes are unstable and decay spontaneously, emitting _and _.14C is a one of these _or _ isotopes. -
- When 14C decays, a neutron is converted to a proton and an electron.
- This converts 14C to 14N, changing the identity of that atom.
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particles and energy unstable or radioactive isotopes |
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| __ is one in which the nucleus decays spontaneously, giving off energy and particles |
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| radioactive isotopes have many applications in biological research: |
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1. radioactive decay rates can be used to date fossils 2. can be used to trace atoms in metabolisms 3. can be used to diagnose medical disorders |
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| is the ability to do work or the capacity to cause change |
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| _is the energy that matter stores because of its position or location |
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| electrons of an atom _ in their amounts of poetential energy |
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| an electrons's state of potential energy is called |
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energy level or electron shell |
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| The farther electrons are from the nucleus, the __ potential energy they have. |
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_ cannot occupy just any location away from the nucleus |
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| which has the lowest energy level or electron shell? which has the highest? |
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-electrons in the first shell closest to the nucleus has the lowest potenital energy -electrons in the outer shell have more potential energy |
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| electrons can only change their position if they? |
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| absorb or release a quantity of energy that matches the difference in potential energy between the 2 levels |
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| the chemical behavavior of an atom is determined by its |
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| _ is the distribution of electrons in its electron shell |
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| the chemical behavior of an atom deprends mostly on the? |
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| the number of electrons in its outermost shell, the valence shell |
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| electrons in the valence shell are known as |
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*atoms with complete valence shell are __ *all other atoms are __ because they have incomplete valence shells |
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unreactive chemically reactive |
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| atoms with incomplete valence shells interact by either |
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| sharing or transferring valence electrons |
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| atoms with incomplete valence shells interact by either sharing or transferrig valence electrons. These interactions typically result in the atoms remaining close together held by an interaction called |
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| is the sharing of a pair of valence electrons by two atoms |
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| _ consists of two or more atoms held together by covalent bonds |
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We can abbreviate the structure of a molecule by substituting a line for each pair of shared electrons,drawing the __. H-H is the _ for the covalent bond between two hydrogen atoms. |
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The __ indicates the number and types of atoms present in a single molecule. Ex. H2 is the __for hydrogen gas. |
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In a ___bond, the atoms share the electron equally. |
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In a __ one atom is more electronegative, and the atoms do not share the electron equally. |
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| a charged atom or molecule is called an |
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| _ is an attraction between anions and cations |
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atoms with postive charge called_ atoms with negative charge called |
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| compounds formed by ionic bonds are __ or __ like NaCl or table salt |
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| the formula for an __ indicated the ratio of elements in a crystal of that salt |
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| most of the strongest bonds in organisms are __ that for a cell's molecules |
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| weak chemical bonds such as _ and _ are also important |
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__ reinforce shapes of large molecules and help molecules adhere to each other |
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| in living cells, the electronegative partners are usually? |
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| molecules or atoms that are very close together can be attracted by |
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| fleeting charge differences |
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| weak attractions are called |
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van der waals interactions |
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| a molecule's shape is usually very important to its |
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| a molecule's shape is fetermined by the postion of |
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| its atoms's valence orbitals |
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| for atoms with electrons in both s and p orbitals, the formation of covalent bonds leads to hybridization of the orbitals to four new orbitals in a |
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| biological molecules recognize and interact with each other with a specificity based on |
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| molecules with similar shapes can have similar |
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for example, morphine, heroin and other opiate drug similar enough in shape that they can bind to the same receptiors as natural signal molecules called___ Binding to receptors produces |
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endorphins euphoria and relieves pain |
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Photosynthesis is an important chemical reaction. green plants combine with water from the air and water from the soil to create __ * this chemical reaction is powered by__ |
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sugar molecules and molecular oxygen, a byproduct *sunlight |
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| humans and other animals depend on photosynthesis for _ |
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the overall process of _ is 6CO2 +6H20 goes to C6H1206 +602 * this process occures in |
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*photosynthesis *sequence of individual chemical reactions |
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*some chemical reactions go to completions_ |
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| all reactants are coverted into products |
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| most chemical reactions are reversible |
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| products of the forward reaction become reactants for the reverse reaction |
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| _ is reached when the forward and reverse reaction rates are equal |
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