Chemistry Unit 1

Chemistry Unit 1 Matter, Transformation, and Energy Chemistry- the study of the properties of materials and the changes that materials undergo. Properties of matter may be:  Physical or Chemical  Quantitative or Qualitative **Measurements must always include units, or the numbers are meaningless** Matter is composed of atoms.  Currently know 118 types of atoms (94 naturally) An element is a pure substance made of only a single type of atom.  Some elements are composed of more than one atom: H2 &O2 are molecules of an element  Atoms- submicroscript particles that constitute the fundamental building blocks of matter.  Compound- 2+ elements o Physical won’t separate but chemical will Matter is either a substance or a mixture. Substance- definite composition and distinct properties  Elements or compounds Mixture- physical combination of 2+ substances  A homogenous mixture is uniform throughout while a heterogenous mixture is not.  Can be separated by physical means into pure components without changing the identities of the components. SOLID, LIQUIDS, GAS Solids & liquids- condensed Kinetic Molecular Theory- interaction of kinetic energy and potential energy of substances Physical properties can be observed without changing the composition of the matter. Physical states: solid, liquid, gas Extensive property: depend on the amount of substance (mass, volume) Intensive properties: do not change with the amount of material (density, boiling point) Chemical properties- property’s potential to undergo change to form a different product.  Combustible  Corrosive  Toxic  Flammable Atomic Structure   Protons & neutrons in nucleus (makes up mass number) Electrons in surrounding area Atomic Mass Since they’re so small, use amu. 1 amu= 1.66054x10^-24 1 g= 6.02214x10^23 amu An atom of same element can have different mass properties. Same chemical properties but not nuclear An atom of the same element can have different mass properties. TO CALCULATE 1. Multiply the decimal fraction of the natural abundance of each isotope by its mass 2. Add the results of these multiplications (decimal fraction x mass of isotope #1) + (decimal fraction x mass of isotope #2) + (decimal fraction x mass of isotope #3) = the atomic mass (atomic weight) of the element Periodic Table Periodic Law- when the elements are arranged in order or increasing mass, certain sets or properties recur periodically. Metals - elements that tend to lose electrons during chemical change, forming positive ions. Nonmetals - substances whose atoms tend to gain electrons during chemical change, forming negative ions. Metalloids (semimetals) - have properties intermediate between metals and nonmetals. • Metalloids form a narrow diagonal band between metals and nonmetals (Al is an exception – classified as a metal). • The properties of metalloids fall between those of metals and nonmetals. The periodic table is arranged in order of increasing atomic number, and can be further classified by: • Group or family: vertical (up and down) column of elements that have similar chemical properties. • Period: horizontal (side to side) row in the periodic table. Alkali Metals     Group 1A All very reactive Tend to lose on electron, forming a cation of 1+ charge Further down you go, more reactive they are Alkaline Earth  Group 2A  Fairly reactive  Forms +2 cations  Loses 2 electrons Halogens  Diatomic molecules  Very reactive nonmetals  Gain an electron  Form anion with -1 charge Noble Gas  Nonreactive  Very stable Allotropes  Same elements bonded in different ways Elements- characterized & identified by unique physical and chemical properties Chemical symbol- assigned based on the name, consisting of capital latter or capital followed by lowercase Diatomic elements- H2, O2, N2, F2, Br2, I2 BrINClHOF Properties of metals  High thermal conductivity  High electrical conductivity  Malleability  Ductility  Metallic luster (shiny) Nonmetals  Brittle  Powdery solids or gases  Right side of periodic table Liquid elements 1. Br2- Bromine 2. Hg- Mercury Gases 1. H2 2. N2 3. O2 4. F2 5. Cl2 6. He 7. Ne 8. Ar 9. Kr 10. Xe 11. Rn Ions- electrically charged groups of atoms May be positive or negative Represented by using the chemical symbol for the atom with a notation of the charge as a superscript to the upper right of the symbol. Metals: Named with the name of the element and adding “ion.” + 3+ 2+ Na sodium ion Al aluminum ion Sr strontium ion Nonmetals: Named by using the root of the element plus “-ide ion” O 2- oxide ion N 3- nitride ion Cl chloride ion Avogadro’s number Mole- relate the amount of substance to the mass in real world quantities 6.022x10^23= 1 mol 1 mol= 6.022x10^23 atoms of that element The lighter the atom, the less mass in one mol of atoms Molar Mass: • The mass in grams of one mole (mass in g/ 1 mol) of a substance. • The molar mass of a compound is always numerically equal to its formula weight. Molar mass is calculated for both elements and compounds. Elements: directly from periodic table Compounds: sum number and type of atoms as for calculation of formula weight.