Question | Answer |
Chemistry | The study of matter and the changes it undergoes |
Methods of Science | Hypothesis Law Theory |
Hypothesis | A tentative explanation or prediction of experimental observations |
Law | A concise verbal or mathematical statement of a relation that is always the same under the same conditions. Laws summarize the facts of nature and rarely change. |
Theory | A unifying principle that explains laws. Explain how or why things happen. Are inventions of the human mind and do change as new facts are discovered. Can never be proven to be absolutely correct |
Qualitative | Nonnumerical observations, physical appearances. Also, whether or not something is there. |
Quantitative | Numerical data. How much of something is there, melting point.... |
Matter | Anything that has mass and occupies space |
3 State of Matter | Solid Liquid Gas |
Solid | Fixed shape Fixed volume |
Liquid | No fixed shape Fixed volume |
Gas | No fixed shape No fixed volume |
Properties of Matter | Physical / Chemical Extensive / Intensive |
Physical Properties | Properties that can be measured and observed without changing the substance's chemical composition example: color, density, melting point, boiling point |
Chemical Properties | How a substance reacts with other substances or undergoes chemical change, such as conversion to another species. |
Extensive Properties | They depend on the amount of matter present example: mass, volume |
Intensive Properties | Independent of the amount of sample present example: melting, temperature, color, density |
Changes of Matter | Physical Chemical |
Physical Changes | A substance changes its physical appearance without changing its composition |
Chemical Changes | A substance is changed into a different substance |
Classification of Matter | Substance: Pure or Compound Mixture: Heterogeneous or Homogeneous |
Substance | A pure form of mater that ha a definite composition, this means with the same atoms and in the same ratio. Examples: salt, sugar, water.... Pure: only one element Compound: two or more elements |
Mixture | A combination of several substances that have a variable composition and can be separated into several substances by physical means Properties of each substance don't change during the separation Exp: milk fat in milk, pigment in paint, minerals in plants |
Two types of Mixtures | Heterogeneous Homogeneous |
Heterogeneous | Each component of the mixture remains separate Exp. concrete, chocolate chip ice cream |
Homogeneous | Same composition throughout the whole mixture (solution) Exp. Soda, Milk |
Separation of Matter | Physical Chemical |
Physical Separation | Each substance in a mixture retains its properties after the separation the separated substances still have the same atom ratio physical changes usually are reversible Exp. boiling alcohol of beer |
Chemical Separation | Separation by changing the substance into a new substances. They will have a new atom ratio and new properties Chemical changes usually are not reversible |
Atom | The smallest particle of an element that has the properties of that element |
Molecules | Two or more atoms combined in definite ratios |
Elements | The simplest substance that is made up of only one type of atom Also, a substance that cannot be broken down into simpler substances by chemical means |
Diatomic elements | H2, N2, O2, F2, Cl2, I2, Br2 HONClBrIF 7 ALSO: P4 and S8 |
Periodic Table | Is a systematic way of organizing known elements based on their properties (into rows and columns |
Rows | Periods |
Columns | Groups or families |
Group 1A | Alkali metals |
Group 2A | Alkaline earth metals |
Group 7A | Halogens |
Group 8A | Noble gases (inert gases) |
Periodic table may be divided in to group types | Main groups Transition-metal groups Inner transitional-metal groups and by metallic properties Metals, nonmetals and semimetals (metalloids) |
Compounds | A combination of two or more elements that are united chemically in definite proportions (CO2, H2O). They always have the same composition They can be broken down into other substances by chemical means to make new substances |
When the substances making up the compound are the same | then it is an element |
When the substances making up the compound are different | then it is a compound |
Law of Constant Composition (Proust) Also Known As: Law of Definite Proportions | All samples of a given compound (same compound), regardless of their source or how they were prepared, have the same proportions of their constituent elements. |
SI for Mass | kg Kilogram |
SI for Length | m Meter |
SI for Time | s Second |
SI for Temperature | K Kelvin |
SI for Amount of Substance | mol Mole |
SI for Volume | L Liter |
Giga | G 10^9 1 000 000 000 |
Mega | M 10^6 1 000 000 |
Kilo | k 10^3 1000 |
Deci | d 10^-1 0.1 |
Centi | c 10^-2 0.01 |
Milli | m 10^-3 0.001 |
Micro | u (mu) 10^-6 0.000 001 |
Nano | n 10^-9 0.000 000 001 |
Pico | p 10^-12 0.000 000 000 001 |
Area | A=(SI Unit)^2 exp. m^2, cm^2, DM^2..... |
Volume | V=(SI Unit)^3 exp. m^3, cm^3, DM^3 (=1L) |
What is the volume of a box in cm^3 if all sides measure 1 inch? What is the volume in dm^3 | |
Difference between Mass and Weight | Mass is a measure of how much matter an object has. Weight is a measure of how strongly gravity pulls on that matter |
Mass | Reflects how much matter is there (kg) |
Weight | Reflects both mass and the force exerted on the mass (lb) |
Density | Density=mass/volume |
Density of water | 1.00 g/cm^3 |
Suppose a box mentioned above has a mass of 55.7 g. what is the density of the box? | |
Temperature | Kelvin Celsius Fahrenheit |
Kelvin | Kelvin = degrees Celsius + 273 Absolute Zero= 0 Freezes Water= 273.15 Boils Water= 373.15 |
Celsius | °C = (°F − 32) × 5/9 Absolute Zero= -273.15 Freezes Water= 0 Boils Water= 100 |
Fahrenheit | °F = (°C × 9/5 )+ 32 Absolute Zero= -460 Freezes Water= 32 Boils Water= 212 |
Scientific Notation | One digit before the decimal point, multiplied by power of tens y.yyyyy x 10^z |
Significant figures | Count all digits from left to right starting with the first non zero digit All zeros to the left of the first nonzero are not significant Zeros between nonzeros are significant 0 to the right of the last nonzero digit are only significant if decimal point |
Significant figures when adding or subtracting | look to see with variable has the greatest place (hundredths, tenths, ones, tens....) as its last significant number. This with be the place reported in your answer. Before as well as after the decimal point |
Significant figures when multiplying or dividing | the number of significant figures is the same as the number with the fewest significant figures |
Dimensional analysis | involves conversion factors in a systematic way to solve problems |
When you heat popcorn, it pops because it loses water explosively. Assume a kernel of corn, weighing 0.125g, weighs only 0.106 g after popping What is the amount of mass lost in kg? What is the amount of mass lost in mg? | |
A runner runs 10km race at an average speed of 16.0 mph. What is the average speed in km/hr? What is the average speed in cm/hr? How long in seconds did it take him to finish the race? | |