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are the stuff that make up:
our bodies and the bodies of other organisms
the physical environment
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All activities of living organisms are powered by |
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are Composed of Elements, in Combinations Called Compounds |
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Living organisms are composed of |
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which is anything that occupies space and has mass (weight). |
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is composed of chemical elements |
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is a substance that cannot be broken down to other substances. |
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(CHON) :
Carbon, Hydrogen, Oxygen, Nitrogen
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Four elements make up about 96% of the weight of most living organisms. They are the main ingredients of proteins, fats and carbohydrates. They are |
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Organisms are Composed of Elements, in Combinations Called |
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is a substance consisting of two or more different elements combined in a fixed ratio. |
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are more common than pure elements in nature! |
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have different characteristics than their individual elements! |
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Consist of Protons, Neutrons, and Electrons |
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Each element consists of one kind of |
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is the smallest unit of matter that still retains the properties of an element |
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Protons: positively charged (+).
Electrons: negatively charged (-).
Neutrons: electrically neutral (no charge).
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Three subatomic particles found in atoms are |
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Neutrons and protons are packed into an atom’s central core or |
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atoms are largely made up of |
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The number of protons an atom contains is called its |
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is the number of protons + the number of neutrons in the nucleus |
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An atom’s atomic mass (or weight) is approximately equal to its |
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the same number of protons
but different numbers of neutrons.
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Different isotopes of an element have:
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the nucleus decays spontaneously, giving off particles and energy (radiation). |
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can be used to date fossils, as tracers in metabolism research, and in medical diagnosis and treatment. |
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Of the three subatomic particles—protons, neutrons, and electrons—only ? are directly involved in chemical activity |
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electron shells that surround the nucleus |
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Electrons occur in energy levels called |
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The Distribution of Electrons Determines an Atom’s |
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determines the chemical properties of the atom! |
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The number of electrons in the outermost shell |
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chemically unreactive (inert) – don’t need anybody else |
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Helium, argon, neon have full outer shells and are |
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completely empty or completely full |
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Atoms are most stable when the outer shell are either |
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sharing, donating, or receiving electrons. |
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These atoms may react with each other by |
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These interactions usually result in atoms staying close together, held by attractions called |
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The strongest kind of chemical bond is a |
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in which two atoms share one or more outer-shell electrons. |
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Two or more atoms held together by covalent bonds form a |
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It depends on the number of additional electrons needed to fill its outer (valence) shell |
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How Many Covalent Bonds Can an Atom Form? |
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The attraction (pull) for shared electrons is called |
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the stronger it will pull shared electrons towards its nucleus. |
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The more electronegative an atom |
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In molecules of only one element, the pull toward each atom is equal, because each atom has the same electronegativity.
The bonds formed are called |
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has atoms with different electronegativities |
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Oxygen attracts the shared electrons more strongly than hydrogen.
So, the shared electrons spend more time near oxygen.
The oxygen atom has a slightly negative charge and the hydrogen atoms have a slightly positive charge.
The result is a |
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is an atom or molecule with an electrical charge resulting from gain or loss of electrons |
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Two ions with opposite charges attract each other.
When the attraction holds the ions together, it is called an |
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When an electron is lost, a |
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When an electron is gained, a |
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Hydrogen, as part of a polar covalent bond, has a partial positive charge.
The charged regions on molecules are electrically attracted to oppositely charged regions on neighboring molecules.
Because the positively charged region is always a hydrogen atom, the bond is called a |
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) Strongest: Covalent Bonds
2) Ionic Bonds
3) Weakest: Hydrogen Bonds
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: join atoms into molecules by sharing electrons |
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join atoms into molecules by losing or gaining electrons. |
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don’t generally join atoms into molecules – they’ll connect one molecule to another or parts of the same molecule to itself.
Weakest bond
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The structure of atoms and molecules determines the |
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the breaking and making of chemical bonds, leading to changes in the composition of matter. |
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materials resulting from the chemical reaction |
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only rearrange the structure and form new relationships.
This is like shuffling and dealing cards.
When playing poker, cards are not created nor destroyed.
Instead, new combinations are formed as the cards are dealt to the players |
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Life’s chemistry is tied to |
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of Earth’s surface is covered by water – this is why Earth is habitable and not the other planets in our solar system |
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occurs when molecules of the same kind to stick together. |
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occurs when two different kinds of molecules stick together. |
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a measure of how difficult it is to break the surface of a liquid. |
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is the amount of energy associated with movement of atoms and molecules in a body of matter. |
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measures the intensity of heat or the average speed of molecules in a body of matter. |
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has the ability to resist huge changes in temperature. |
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is able to absorb a great deal of heat energy without a large increase in temperature, and it is able to release heat energy without a huge decrease in temperature. |
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– it is less dense as a solid than a liquid because of hydrogen bonding |
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is a liquid consisting of a uniform mixture of two or more substances. |
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The dissolving agent is the |
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The substance that is dissolved is the |
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is one in which water is the solvent. |
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from the polarity of its molecules |
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Water’s versatility as a solvent results |
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Polar or charged solutes dissolve when water molecules surround them, forming |
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A compound that releases H+ in a solution is an |
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A compound that accepts H+ is a |
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describes how acidic or basic a solution is. |
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The pH scale ranges from 0 to 14, with zero the most acidic and 14 the most basic.
Each pH unit represents a tenfold change in the concentration of H+ |
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is a substance that minimizes changes in pH.
They accept H+ when it is in excess
They donate H+ when it is depleted
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exist in blood and other body fluids to maintain pH stability around 7.0 (neutral) |
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acid precipitation, which is rain, snow, or fog with a pH lower than 5.2. (Uncontaminated rain has pH of 5.6) |
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Sulfur and nitrous oxides react with water in the air to form acids (sulfuric and nitric acids)
These acids fall to Earth as |
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CO2 dissolving in seawater (produces carbonic acid) lowers ocean pH in a process known as |
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interferes with corals ability to produce their skeletons or shells. |
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