Chapter 2 Chemistry

Chemistry Matter  anything that has mass & takes up space Matter  anything that has mass & takes up space Mass  amount of matter an object has Mass  amount of matter an object has Elements  pure substances that cannot be broken down into simpler kinds of matter Elements  pure substances that cannot be broken down into simpler kinds of matter Important elements : C, O, H, N Important elements : C, O, H, N

Chemistry Atom  simplest particle of an element Atom  simplest particle of an element  the properties of an atom determine the properties of that matter Nucleus  core of an atom ; protons & neutrons Nucleus  core of an atom ; protons & neutrons 1.Protons  + charge, mass 1 amu 2.Electrons  - charge, no mass 3.Neutrons  no charge, mass 1 amu

Electrons  outside the nucleus on shells 2 on the first & 8 on the rest

Periodic Table Arranged in increasing atomic # Arranged in increasing atomic # Atomic # = number of protons Atomic # = number of protons # of Protons = number of electrons # of Protons = number of electrons Atomic mass = # of protons + # of neutrons Atomic mass = # of protons + # of neutrons Each column has the same number of outside ( valence electrons) Each column has the same number of outside ( valence electrons)

Chemistry Compound  pure substance of 2 or more elements combined Compound  pure substance of 2 or more elements combined H 2 O, CH 4, (NH 4 ) 2 SO 4

Bonds Bonds  attachments of atoms in a compound Bonds  attachments of atoms in a compound 1.Covalent  electrons shared 2.Ionic  1 atom gains electrons & 1 atom loses

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Chemistry Molecule  simplest part of a substance that has all the properties of that substance and can exist by itself Molecule  simplest part of a substance that has all the properties of that substance and can exist by itself  can be two atoms of the same element or more than one type of element Ex: O 2, N 2, C 6 H 12 O 6 Ex: O 2, N 2, C 6 H 12 O 6

Chemistry Reaction  two substances interact & change identity Reaction  two substances interact & change identity Reactants  Products H 2 + O 2 → 2H 2 O ↔ Means that the reaction can go both ways ↔ Means that the reaction can go both ways

Chemistry Exothermic  reactions that release heat/ energy Exothermic  reactions that release heat/ energy Endothermic  reactions that absorb heat/energy Endothermic  reactions that absorb heat/energy Activation energy  energy needed to start a reaction Activation energy  energy needed to start a reaction

Chemistry Catalyst  speed up reactions by lowering activation energy Catalyst  speed up reactions by lowering activation energy Enzymes  are biological catalysts Enzymes  are biological catalysts Substrate substance that binds to enzymes Substrate substance that binds to enzymes

Enzymes Functions Are substrate specific Are substrate specific Lock & key fit Lock & key fit Speed up reactions by lowering activation energy Speed up reactions by lowering activation energy

Chemistry Solutions  are mixture where one substance is dissolved in another Solutions  are mixture where one substance is dissolved in another Solute  substance that gets dissolved Solute  substance that gets dissolved Ex: Kool Aid Powder Solvent  does the dissolving Solvent  does the dissolving Ex: Water – water is the universal solvent

Chemistry Concentration  amount of solute per amount of solution Concentration  amount of solute per amount of solution  tells us how spread out the particles are Saturated  no more solute can be added Saturated  no more solute can be added  it has the maximum amount of solute Aqueous  something is dissolved in water (aq) Aqueous  something is dissolved in water (aq)

Chemistry Dissociation of water Dissociation of water H 2 O ↔ H + + OH - hydrogen ion + hydroxide ion Ions  are any particle that has a charge Ions  are any particle that has a charge

Chemistry ACIDS & BASES ACIDS & BASES Acids  form hydrogen ions in solution (H+ ) Acids  form hydrogen ions in solution (H+ )  have a sour taste Ex: HCl  H + + Cl - Bases  form hydroxide ions in solution (OH-) Bases  form hydroxide ions in solution (OH-)  have a bitter taste Ex: NaOH  Na + + OH –

Chemistry pH Scale  measures the concentration of hydrogen ions in solution pH Scale  measures the concentration of hydrogen ions in solution  Range is 0-14  0 – 7 is an acid  is basic (alkaline) → 7 is neutral (water) Buffer  substances that neutralize a small amount of acid or base. Buffer  substances that neutralize a small amount of acid or base.  maintain the pH within our bodies.