Basic Chemistry Atoms, Elements and How They Behave

Start Small End Big Atoms  Elements  Compounds  Cells  Tissues  Organs  Organ Systems  Organisms

Smallest amount of an element that still has the properties of that element. Made up of: - Protons, P +, Charge of +1 - Neutrons, N, zero charge - Electrons, e -, charge of -1 ATOM:

Structure of an Atom P P N N e e Nucleus: Center of atom, where protons and neutrons are located Orbit: Area outside nucleus where electrons are in constant motion

Orbits spin and rotate in three dimensions. P P N N e e Structure of an Atom

Orbits spin and rotate in three dimensions. Structure of an Atom

Each Orbit is a specified distance from the nucleus. P P N N e e Structure of an Atom

P P N N e e Nucleus Orbit e e e e e e e e e

Structure of an Atom

Each type of atom has its own number of e, P and N P P N N e e Structure of an Atom

The different combination of P, N and e make each element unique P P N N e e Structure of an Atom

Normally, all the “+” of the protons and the “-” from the electrons balance out and the overall charge of the atom is zero. Structure of an Atom

What if an atom loses an electron? P P N N e Structure of an Atom P P N N e e Atom becomes positive

P P N N e e Structure of an Atom What if an atom gains an electron? - Atom becomes negative e -

Any charged atom is called an ion Structure of an Atom - Positive ions are called cations - Negative ions are called anions

The Periodic Chart Atomic number is the number of protons Atomic Mass is the “approximate” number of protons + neutrons Assume Electrons = Protons (except Ions)

Atomic Mass = Protons + Neutrons Why don’t the electrons figure in?

Drawing Atoms: Each orbit can hold a maximum number of electrons. - Orbit 1: holds a max of 2 - Orbit 2: holds a max of 8 - Orbit 3: holds a max of 8 You must fill the inner orbits before adding electrons to the outer orbits.

Examples 29 Cu 63

Examples 36 Kr 83

Examples 12 Mg 24 P P P P P P P P P P P P N N N NN N N N N N N N e e e e e e e e e e e e

Valence electrons Electrons in outer most orbit Atoms want a complete outer orbit They will bond with atoms that fill the orbit

Examples Look at the column on periodic table to figure out Valence electrons Na __________ Cl ____________

Examples Look at the column on periodic table to figure out Valence electrons C __________ N____________

Main Elements in Human Body Oxygen Carbon Hydrogen Nitrogen

Main Elements in Earth’s crust Oxygen Silicon Aluminum Iron

Compounds Two or more atoms bonded together in a set proportion H 2 0 vs. H 2 O 2 - what is different? C0 2 vs. CO

Compounds Parts are chemically bound together Definite proportions required Properties of a compound are different from the properties of the elements that make up that compound

Mixtures Mixtures have “ingredients” that do not bind chemically with each other Each ingredient keeps its own properties Definite proportions not required Types: solution, suspension, colloid

Mixtures Solution: homogeneous; even throughout; solute (substance) completely dissolves in solvent (liquid) Suspension: Heterogeneous; looks even if shaken; but particles settle to bottom

Mixtures Colloid: heterogeneous BUT does not settle; sort of in between the other two.

Mixtures vs. Compounds Look at your notes: What are three big differences between Mixtures and Compounds?

Types of bonds that form Compounds Ionic Bond- One atom gives an electron to the other

IONIC: Creates opposite charge that holds atoms together

Types of bonds that form Compounds Covalent- each atom shares electrons with the other

Chemical Reactions Change in the arrangement of atoms that creates a different substance A + B  C synthesis reaction A  B + C decomposition A + B  C + D Displacement

Chemical Reactions Reactants: The “stuff” you start with Products: The “stuff” you end up with A + B  C ReactantsProducts

Chemical Reactions Al + O 2  Al 2 O 3 C 2 H 6 + O 2  CO 2 + H 2 O H 2 0  H + + OH -

Properties of Water Water is held together with special covalent bond called polar covalent bond - Means water has poles, or ends. - O is the negative end - H’s are the positive end

Properties of Water

Cohesion: Water molecules stick together because of charges

Cohesion Creates Surface tension - allows stickbugs to walk on water!

Adhesion Water molecules stick to other charged substances like glass Glass stirring rod

Water is the Universal Solvent Anything with a charge will attract water molecules and dissolve Ionic and polar molecules have charge Nonpolar molecules (like fat) do not have charge and will not dissolve

Acids and Bases Acids: a chemical that when dissolved in water releases a hydrogen ion (H + ) HX (in water)  H + + X -

Properties of Acids Taste sour – think of lemon Turn litmus paper from blue to red Corrodes Metal Examples: Sulfuric Acid, Lemon Juice, Battery Acid

Acids and Bases Base: a chemical that when dissolved in water releases a hydroxide ion (OH - ) XOH (in water)  OH - + X +

Properties of Bases Taste bitter – cough meds. Turn litmus paper back to blue after acid turns it red Can cause serious burns Examples: Bleach, KOH, NaOH

Acids and Bases - Examples NaOH + H2O  Na + + OH - + H2O HCl + H2O  H + + Cl - + H2O

Acids and Bases will “cancel” each other out When an Acid and a Base are mixed together they will “Neutralize” each other and create Water and a Salt This is a Neutralization Reaction

Neutralization Reaction HCl + NaOH  NaCl + H 2 O A Salt Water HNO 3 + KOH  KNO 3 +H 2 O A salt Water

Concept of pH pH = power of Hydrogen pH = power of Hydrogen A way of measuring how many Hydrogen ions, H+, there are in a solution A way of measuring how many Hydrogen ions, H+, there are in a solution Determines whether a solution is an acid or a base Determines whether a solution is an acid or a base

Neutral (water) AcidBase High H + Low OH - H + = OH - High OH - Low H + pH Scale – a measure of the concentration of Hydrogen Ions

Concept of pH Where is the “safe” pH? Where is the “safe” pH? pH must stay between in the human body Another factor that must maintain homeostasis

Concept of pH Are there exceptions? Are there exceptions? Stomach is acidic Intestines are basic Buffers are necessary weak acids or bases that react with strong acids or bases to prevent sudden changes in pH

What is the pH of Rain water?? Usually between Water reacts with CO2 in air to form Carbonic Acid (H2CO3)

What is the pH of Rain water?? Acid Rain: - Rain water reacts with pollutants such as Sulphur dioxide and Nitrogen oxides in air - Forms Sulphuric Acid, Nitric Acid, Ammonium Sulphate - Decreases pH even further