Chapter 2 - Chemistry Notes PDF

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Matter and Energy • Matter - anything that occupies space and has mass (weight) Energy - the ability to do work – Potential - the stored energy in an object or system because of its position or configuration. – Kinetic - the energy of a body or a system with respect to the motion of the body or of the particles in the system. • can be transferred from one moving object to another, say, in collisions. Composition of Matter • Elements—fundamental units of matter – _________________ of the body is made from four elements • Carbon (C) • Oxygen (O) • Hydrogen (H) • Nitrogen (N) • Atoms—building blocks of elements Subatomic Particles • Nucleus – Protons (p+) – Neutrons (n0) • Orbiting the nucleus – _________________ (e–) • Number of protons equals numbers of electrons in an atom •

Periodic Table • _________________ are listed by a symbol • Element’s Greek or Latin name is the abbreviation • First 94 elements occur in nature 1

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• Groups - ________________ • Periods – _______________ Dmitry Mendeleyev Trends of Periodic Table Sulfur Group: _____________ Period: ______________ Atomic Number: _______ Symbol: __________ Atomic Mass: ___________ Identifying Elements • •

______________________________ – equal to the number of electrons or protons that the atom contains Atomic mass number – _______________________________ – atomic mass units

Isotopes • Atoms of an element that differ in the number of their ____________ are called

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isotopes. – All elements have isotopes – Defined by their mass number • Total number of neutrons and protons in the nucleus Carbon 12 – 6 protons; 6 neutrons; Carbon 14 – 6 protons; 8 neutrons __________________ – is when the atoms will spontaneously emit subatomic particular or energy (radiation) when their nucleus breaks down – Uranium – Nuclear power plant – Japan

Electrons and Bonding 2

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Electrons occupy energy levels called ___________________ Electrons closest to the nucleus are most strongly attracted • Each shell has distinct properties – The number of electrons has an upper limit – Shells ___________ to the nucleus fill first • Bonding involves interactions between electrons in the outer shell (valence shell) • Full valence shells do not form bonds • ________________________ are the outermost electrons of an atom. Stable (Inert) Elements • Atoms are stable (inert) when the _________________ shell is complete • How to fill the atom’s shells – Shell 1 can hold a maximum of ______ electrons – Shell 2 can hold a maximum of 8 electrons – Shell 3 can hold a maximum of 8 electrons • Atoms will gain, lose, or share electrons to complete their ____________ orbitals and reach a stable state • _________________________ – Atoms are considered stable when their outermost orbital has 8 electrons – The exception to this rule of eights is Shell 1, which can only hold 2 electrons

Reactive Elements • Valence shells are ________________________________________________ • Tend to gain, lose, or share electrons – Allow for _________________________________________, which produces stable valence Electronegativity • The ability to ___________________________________ from other atoms – Not the same as charge 3

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• Depends upon its size and number of vacancies it has Molecules and Compounds • Molecule - two or more atoms of the ____________________________ elements combined chemically • Compound - two or more atoms of _______________________ elements combined •

chemically Mixture – intermingling of two or more substances – Liquid mixture is called a ________________.

Reduction – Oxidation • Reduction-oxidation (redox) reactions – coupled (occur together, simultaneously) chemical reactions that occur when a _________________ of electrons, hydrogens or oxygen takes place. • •

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Oxidation – loss of electrons, hydrogen, or both, or the gain of oxygen. Reduction – ___________________, hydrogen, or both, or the loss of oxygen.

The accumulation and transfer of ________________ is essential to the synthesis of new energy-storage molecules such as ATP. Electron accumulation builds ________________, while electron transfer releases energy in small, manageable amounts.

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TYPES OF BONDS Types of Bonds Ionic Covalent Hydrogen Strength of bonds! – know this chart in order!! Review Valence Electrons •

Study the diagram below, determine number of valence electrons each atom has, and whether or not it would be considered chemically reactive or inert:

Ions •

Result from the loss or gain of electrons – ______________________ • negative due to gain of electron(s) – Chloride – _____________________ • positive due to loss of electron(s) – Sodium Ionic Chemical Bonds 5

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Ionic bonds – A strong mutual attraction of __________________________ ions

– Atoms become stable through the transfer of electrons – Form when electrons are completely transferred from one atom to another Covalent Chemical Bonds • Covalent bonds – Atoms become stable through ____________________________ – Electrons are shared in pairs – Single covalent bonds share one pair of electrons – _____________________________ share two pairs of electrons • Single Covalent Bond (Picture) • Double Covalent Bond (Picture) • Covalent Bonding – molecules (Picture) Covalent Bonds - nonpolar • Covalent bonds are either nonpolar or polar – Nonpolar • Electrons are shared _________________ between the atoms of the molecule • Electrically neutral as a molecule • CO2 – Polar • Electrons are ____________________ between the atoms of the molecule • Have a positive and negative side or pole • WATER Hydrogen Chemical Bonds • Hydrogen bonds – _____________________ chemical bonds – Hydrogen is attracted to the negative portion of polar molecule – Provides attraction between molecules • Hydrogen Bonding (Picture) – Do you know the changes of states??? • Properties of Water – High heat capacity – High heat of vaporization 6

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– Universal solvent – Molecules are cohesive and adhesive – High surface tension – Frozen water is less dense than liquid water Importance of Water • Water has an indispensable role as the _________________ in biological systems – ___________________ – a substance, usually a liquid that can dissolve other substances – Solute – dissolved in a solvent • It is the single most abundant component of cells and organisms • About 75-85% of a cell by weight is water • Its chemical characteristics make water indispensable for life • A solvent is a fluid in which another substance, the solute, can dissolve • Water is able to ________________ a large variety of substances, due to its polarity • Most of the molecules in cells are also ____________________ and so can form hydrogen bonds, or ionic bonds with water Solutes • _________________________ - Solutes that have an affinity for water and dissolve in it easily – generally polar molecules or ions – Many small molecules - sugars, organic acids, some amino acids • Hydrophobic - Molecules not easily soluble in water – such as _____________ and ________________ in membranes – generally nonpolar molecules Water Molecules are Polar • _______________________________________ of electrons gives water its polarity • The water molecule is _____________ rather than linear • The oxygen atom at one end of the molecule is highly _____________, drawing the electrons toward it • This results in a partial negative charge at this end of the molecule, and a partial positive charge around the hydrogen atoms Water Molecules are Cohesive • Because of their polarity – water molecules are ___________________ to each other 7

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– orient so the electronegative oxygen of one molecule is associated with the electropositive hydrogens of nearby molecules • Such associations, called ________________________, are about 1/10 as strong as covalent bonds Hyrdogen Bonds and cohesiveness •

Water is characterized by an extensive network of hydrogen-bonded molecules, which make it cohesive

– _________________ – resist separating from each other. • Examples: Evaporation - is resisted by the hydrogen bonding that keeps the molecules together • _____________________________ • The combined effect of many hydrogen bonds accounts for water’s high – Surface tension – Boiling point – Specific heat – Heat of vaporization Surface Tension of water • Is the result of the collective strength of vast numbers of _____________________ • Allows insects to walk along the surface of water without breaking the surface • Allows water to move ________________ through conducting tissues of some plants Water has a high temperature stabilizing Capacity • High specific heat gives water its temperature-stabilizing capacity – _____________________ - the amount of heat a substance must absorb to

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raise its temperature 1oC • The specific heat of water is 1.0 calorie per gram, much higher than most liquids Water therefore changes temperature relatively ______________________ from extreme temperature changes *Without this characteristic of water, energy released in cell metabolism would cause overheating and death

Heat of Vaporization • the amount of energy required to convert 1 gram of liquid into vapor – This value is _____________ for water because of the many ______________ that must be broken 8

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The high heat of vaporization of water makes it an __________________

Water Dissociation • Water can dissociate into "_______________" (H+) • and _____________ ions (OH-). • The number of hydrogen and hydroxyl ions in a sample of H2O is equal and constant pH • • • • • •

_____________________ – refers to the amount of a particular solute that is dissolved in a given volume of fluid Neutral – number of hydrogen ions and the number of hydroxide ions are equal – One unit decrease refers to a ______________________ decrease in H+ ions As a solution gets more acidic (as [H+] increases), the pH ____________________. As a solution gets more basic (higher [OH-]), the pH increases. As the pH of a solution decreases by one pH unit, the concentration of H+ increases by ten times. As the pH of a solution increases by one pH unit, the concentration of OH- increases by ten times.

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Acids – _______________ hydrogen ions, lower pH – Higher the number of H+, the lower the pH

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Salt – ionic compound made of a cation and an anion, other than hydroxide – The product besides water of a _____________________ reaction Buffer – set of chemicals that can keep the pH of a solution ________________ – When a base is added to an unbuffered fluid • Number of _______________ ions increases • pH rises – If the fluid is buffered, the addition of the base causes: • the buffer to release ________________ -> combine with OH- to form ________ – A buffer can only neutralize only so many ions. • Slightly more than the limit will change the pH drastically.

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