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Introduction to Chemistry Honors Biology Ms. Kim

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1 Introduction to Chemistry Honors Biology Ms. Kim

2 Composition of Matter Matter - everything in universe is composed of matter (“stuff”) Matter is anything that occupies space or has mass Mass – quantity of matter an object has Weight – pull of gravity on an object

3 Elements Pure substances that cannot be broken down
Made of a single type of atom (group of atoms of the same type) More than 100 elements (92 naturally occurring)

4 Elements Atomic # of an element Mass # of an element Therefore….
Equals the # of protons AND the # of electrons Unique for each element Mass # of an element Equals the SUM of protons and neutrons Therefore…. Protons + Neutrons = Mass # Mass # - Atomic # = Neutrons

5 CHONPS All living things are made up of 4 Biological macromolecules (which we will be talking about later). Carbohydrates Lipids Proteins Nucleic Acids Biological macromolecules are made almost entirely of just 6 elements: Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N) Phosphorus (P) Sulfur (S) CHNOPS The most important element is CARBON!

6 Each element unique chemical symbol
96% of the mass of an organism is composed of 4 elements (carbon, hydrogen, oxygen (65%) and nitrogen  “CHON”) Each element unique chemical symbol Consists of 1-2 letters First letter is always capitalized Other 4% consists of calcium (Ca), phosphorus (P) potassium (K), sulfur (S), sodium (NA), and other sevaral trace elements such as Fe (iron) needed to transport oxygen in your blood and Chromium (Cr) (needed for your cells to bread down sugars for usuable energy)

7 Atoms Smallest and simplest piece of matter Atom have 3 subparticles:
Protons (Positive +) Neutrons (Neutral 0) Electrons (Negative -) Millions of atoms could fit in a space the size of the period at the end of a sentence. And it would take you more than 1 trillion years to count the number of atoms in a single grain of sand.

8 The Nucleus Middle of the atom (central core)
Holds positive charged protons and neutral neutrons Positively charged Contains most of the mass of the atom

9 The Protons All atoms of a given element have the same number of protons #of protons = the atomic number # of protons (+’s) = # of electrons (-’s) (in a neutral atom)

10 The Neutrons The number varies slightly among atoms of the same element Different number of neutrons produces isotopes of the same element

11 Isotopes \ Isomers Isotopes = an element with the same # protons, but different # neutrons Ex: C12 vs. C14 Isomers = compounds with the same molecular formula, but different structures

12 Atomic Mass Protons & neutrons are found in the nucleus of an atom
Protons and neutrons each have a mass of 1 amu (atomic mass unit) The atomic mass of an atom is found by adding the number of protons & neutrons in an atom What is the atomic mass of an oxygen?

13 Practice Problems! How many protons does a sodium (Na) atom have?
How many neutrons does a fluorine (F) atom have? What is the atomic mass for oxygen (O)? What is the atomic number for phosphorus (P)?

14 The Electrons Negatively charged high energy particles with little or no mass Travel at very high speeds in different energy levels Energy levels are different distances from the nucleus

15 Energy Levels Electrons in the same energy level are approximately the same distance from the nucleus Outer energy levels have more energy than inner levels Each level holds only a certain number of electrons

16 Electron Shell Electron Shell Shells:
Inner most  can hold at most 2 e- Outer most  can hold at most 8 e- Third outer most  can hold at most 8 e- Elements want to have full shells, because this makes them stable! Carbon (neutral) Atomic # = 6  6 total electrons 2 electrons fill the inner most shell 4 will be in the outer most shell This means Carbon has 4 VALENCE electrons Can bond to 4 other atoms!

17 Periodic Table Elements are arranged by their atomic number on the Periodic Table The horizontal rows are called Periods & tell the number of energy levels Vertical groups are called Families & tell the outermost number of electrons


19 Compounds Most atoms do not exist by themselves
Atoms combined with other atoms to form compounds

20 Compounds A compound is a pure substance made up of atoms of two or more elements 2 types: molecules or ionic compounds Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

21 Compounds Compounds : Examples
Have different properties than individual elements Ex: NaCl = 1 sodium + 1 chloride  table salt Ex: H20 = 2 hydrogen + 1 oxygen  water Ex: NaOH = 1 sodium + 1 oxygen + 1 hydrogen Ex: CO2 = 1 carbon + 2 oxygen

22 Compounds What happens when the ratio of atoms changes? H20 vs. H2O2
When the ratio of elements in a compound changes, the physical and chemical properties change too

23 Molecules Molecule is two or more atoms held together by covalent bonds. Almost all of the substances that make up organisms, from lipids to nucleic acids to water, are molecules held together by covalent bonds. A compound is a type of molecule. All compounds are molecules, but all molecules are NOT compounds. Molecule Examples: H2O, O2, O3 Compound Examples: NaCl, H2O

24 Chemical Formulas 2H202  2H2O + O2
Subscript after a symbol tell the number of atoms of each element H20 has 2 atoms of hydrogen & 1 atom of oxygen Coefficients before a formula tell the number of molecules 3O2 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

25 Bonds Molecular “glue” Holds atoms together to form compounds Valence electrons are involved in bonding Valence electrons = electrons on outer most energy level. Atoms are most stable when their outer most energy level is filled

26 Bonding What holds atoms together?
Atoms are held together by chemical bonds Goal: to fill outer electron shell…so atoms BOND together (share or give away/take electrons) to get a full outer shell 2 main types: Ionic bonds Covalent bonds

27 Bonds Single Double Triple
Bonds SIZE decreases as you increase # of bonds Bonds STRENGTH increases as you increase # of bonds

28 Covalent Bonding Formed when two atoms share one or more pairs of electrons. (‘co’ means ‘together’) When two or more atoms are joined by covalent bonds, we call this a molecule Very strong Single, double, triple bonds H = 1 bond O = 2 bonds N = 3 bonds C = 4 bonds

29 Because positive and negative electrical charges attract each other ionic bonds form

30 Ionic Bonds Formed when one or more electrons are transferred from one atom to another Atoms lose or gain electrons If an atom loses electrons  becomes positively charged (+) If an atom gains electrons  becomes negatively charged (-) Atoms that have gained or have lost electrons are ions Ex: Salt (NaCl)

31 Cations & Anions Cation = when an atom loses an electron, it becomes more positively charged Positive Ion = Cation Remember: Cats have PAWS and are POSITIVE Ex: Removing an electron from a K (potassium) atom will….create a POSTITIVE ION = CATION Anion = When an atom gains an electron, it becomes more negatively charged Negative Ion = Anion Ex: If a Cl (chlorine) atom gains an electron…creates a NEGATIVE ION = ANION

32 States of Matter Atoms are in constant motion (called kinetic energy)
The rate at which atoms or molecules in a substance move determines its state

33 Level of Organization Subatomic particles (p+, e-, n0) atom (O)
Element (O) molecule (O2) macromolecules (lipid) Cell (blood cell) <--life begins here Tissue (epithelia tissue) Organ (lung) Organ system (Respiratory System) Organism (Panthera leo (lion))

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