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Matter Classification. Chemistry Chapter 1. Try to Answer the Following Questions. 1. A compound is formed by… A single element Two or more atoms Two or more nuclei Electrons and neutrons Which statement best describes atoms and molecules in a liquid? They vibrate rapidly
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Matter Classification Chemistry Chapter 1
Try to Answer the Following Questions 1. A compound is formed by… • A single element • Two or more atoms • Two or more nuclei • Electrons and neutrons • Which statement best describes atoms and molecules in a liquid? • They vibrate rapidly • They form a definite structure • They slide past each other • They cannot be rearranged • What is the process of a liquid changing to a gas called? • Ice melting into water is a physical or chemical change? • Which state of matter has neither a definite shape nor definite volume?
How did you do? • “B”: two or more atoms • “C”: atoms and molecules in a liquid slide past each other • Evaporation • Physical • Gas
Chemistry • The study of the composition, properties, and behavior of matter.
What does a Chemist do? • Develop new products (meds., cosmetics) • Find methods to reduce pollution/clean up environment • Teaching • Analyzing substances • Quality of manufactured products
Hypothesis vs. Theory vs. Scientific Law • A HYPOTHESISis an idea that you can test through experimentation. • A THEORY is a tested explanation of WHY something happened. (Cannot prove) • SCIENTIFIC LAW is a statement explaining WHAT happened in an experiments. (Can prove)
Why does it “matter”? • What is matter? • “Everything that takes up space and has mass” • What is mass? Amount of matter an object contains *This is NOT the same as weight
Substances vs. Mixtures • Matter is broken into categories. Matter can be either a substance or a mixture. • A substance has a constant composition. This means that no matter the sample it will always have the same physical properties (looks the same).
Substances Elements • Made up of only one type of atom. • Look at the periodic table! • Ex: Ca, K, Cl Compounds • Made up of two or more types of atoms. • Look at periodic table! • Ex: Table Salt, NaCl Glucose, C6H12O6
Mixtures • A mixture is a physical blend of two or more substances. It has a variable composition, so each sample taken will have different amounts of each substance. • Mixtures are ALWAYS physical changes.
Heterogeneous Mixtures -variable composition -more than one phase (can visibly see differences) -can be physically separated Examples: tossed salad, gravel mix, rock, river water
Homogeneous Mixtures -constant composition -one phase (called a solution) -easily confused with substances Examples: salt water, kool-aid
Separating a Mixture • There are several ways to separate a mixture. A good way to figure out if matter is a substance or a solution is to see if you can separate it into parts by doing one of the following: • Physical separation • Filter (particle size, uses gravity) • Magnet (magnetism) • Decanting-pouring off a liquid (density) • Distillation (boiling point) • Centrifuging (density) • Chromatography (separates based on solubility) • Crystallization
Physical Properties • Matter contains both physical and chemical properties. • A physical property is a quality of a substance that is observed without changing the substance’s original composition. • Examples: Color, mass, density, hardness, odor, boiling point, solubility
Chemical Properties • Chemical properties are a little more difficult to determine. A chemical property is the ability of a substance to undergo chemical reactions. • Examples: Rot, rust, decompose, decay, grow ferment
Chemical vs. Physical Changes • Chemical Change • A change in the composition of a substance OR • Changing a substance to form a new substance • Examples: fermenting, rotting, burning, color change, gas given off, heat • Physical Change • A change in a substance without a change in its composition • Examples: mixing, cutting, changing from a solid to a liquid, dissolving, boiling
Figure it out- Chemical or Physical? • Metals are shiny • Milk gets sour when left out • Metals can be made into wires • Bread rises when cooked • Nonmetals are not able to conduct electricity P, C, P, C, P