If an atom has 15 protons how many electrons does it have? Where do each subatomic particle reside in an atom?
conversion Given that 1.00cm3= 1.00mL… How many Kiloliters of water are in one million cm3??? Answer?= 1 kL
Conversion If you have 1000 yen how many euro do you have? (yen to dollar =0.0119, euro to dollar= 1.274)
Conversion If you run a 5.00 km marathon how many miles are you running? (1.609 km= 1 mile) Answer= 3.11 miles
Conversion Review There are 4840 square yards in every acre. Since there are 1.196 square yards in every square meter, how many square meters are in 4 acres?
Predicting atomic structure from the Periodic table Atomic # is the number of protons Atomic mass is the sum of protons and neutrons # of electrons = # of protons in an atom # of electrons in ions is larger or smaller than number of protons by the opposite of the charge
Matter Matter is a general term for all the substances in which all objects are made. Matter is divided into two categories: Pure substances Mixtures
Pure substances A pure substance can be defined as a sample of matter that consists of only one component with definite physical and chemical properties and a definite composition. Pure substances cannot be broken down into simpler substances by chemical means Examples of a pure substance may be an element or a compound
Pure Substances Nitrogen Carbon dioxide hydrogen
Mixtures a combination of two or more phases that are not chemically united and do not exist in fixed proportions to each other. Basically two things are mixed together and can be separated Mixtures can be either heterogeneous (made of two different compositions )or homogeneous (a mixture of the same composition)
Examples of mixtures homogeneous Air with no clouds Sugar water Salt water Milk heterogeneous Gravel Salt and pepper Sand Some salad dressings (Italian)
Review Which are pure subtances and which are mixtures? Lemonade Helium gas Soil Deionized Water Ammonia Ceasar Dressing
Chemical vs. physical change chemical A change in the composition of the elements in the compound. A microscopic change physical Difference in the way that something looks A different state of matter If the solid is in solution or not
Review questions What would you consider is the most common physical change in your daily life? What is the most common chemical change? If you burn food is that considered a physical change or a chemical change? Why or why not?
Review Questions As food is digested does it go through a physical change or a chemical change? When making Kool aid does a physical or chemical change take place What is happening to the atoms on a microscopic level in a physical change and in a chemical change?
Your company makes dresses, each dress requires 4 yards of fabric, unfortunately your supplier only sells fabric by the meter. How many meters of fabric do you need to make 39 dresses? (1 yard = 0.9144 meters)
Bohr Contributions Bohr established the idea of electrons being restricted to certain energy levels that surround the nucleus This was based on a experimental observation that atoms only absorb and release specific energies when light energy is added
Modern Atomic Theory The location of electrons in an atom is given in terms of probably This is because we can only predict where an electron will be at a certain time The location of highest probably is called an orbital or electron cloud
Orbital Trends Orbitals that are closer to the nucleus have less energy than ones farther away Electrons can only occupy orbitalsand certain energy levels Ex: n=1 or a d orbital Electrons can change energy levels if enough energy is added to the atom
Review Question What idea did Bohr establish? What experimental evidence did Bohr have to support this idea? What is the most probable area for an electron to be located called? Can we ever be sure where an electron is located? What kind of energy can be added in order to change the orbital level of an atom?