Matter – Properties & Changes Honors Chemistry Chapter 3

1. Substance s Section 3.1 – Properties of Matter Matter is anything that has mass and takes up space. Matter is everything around us. Matter with a uniform and unchanging composition is a substance.

2. Physical Properties of Matter A physical property is a characteristic that can be observed or measured without changing the sample’s composition.physical property Extensive properties are dependent on the amount of substance present, such as mass, length, or volume.Extensive properties Intensive properties are independent of the amount of substance present, such as density.Intensive properties

3. Chemical Properties of Matter The ability of a substance to combine with or change into one or more other substances is called a chemical property.chemical property –The ability of Iron to form rust –The inability of a substance to change into another substance –Copper turning green in the air

4. Observing Properties of Matter A substance can change form–an important concept in chemistry. Chemical properties can change with specific environmental conditions, such as temperature and pressure. Observations of properties may vary depending on the conditions of the immediate environment.

5. States of Matter The physical forms of matter, either solid, liquid, or gas, are called the states of matter.states of matter Solids are a form of matter that have their own definite shape and volume.Solids The particles of matter in a solid are very tightly packed.

States of Matter (cont.) Liquids are a form of matter that have a definite volume but take the shape of the container.Liquids The particles in a liquid are not rigidly held in place and are less closely packed than are the particles in a solid: liquid particles are able to move past each other. Gases have no definite shape or volume. They expand to fill their container.Gases Compared to solids and liquids, the particles of gases are very far apart. Vapor refers to the gaseous state of a substance that is a solid or liquid at room temperature.Vapor

End of Section 3.1

6. Physical Changes Section 3.2 – Changes in Matter A change that alters a substance without changing its composition is known as a physical change. physical change A phase change is a transition of matter from one state to another.phase change Boiling, freezing, melting, and condensing all describe phase changes in chemistry.

7. Chemical Changes A change that involves one or more substances turning into new substances is called a chemical change.chemical change Decomposing, rusting, exploding, burning, or oxidizing are all terms that describe chemical changes.

8. Conservatio n of Mass The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, it is conserved.law of conservation of mass The mass of the reactants equals the mass of the products. mass reactants = mass products

End of Section 3.2

9. Mixtures A mixture is a combination of two or more pure substances in which each pure substance retains its individual chemical properties.mixture A homogenous mixture is a mixture where the composition is constant throughout.homogenous mixture Homogeneous mixtures are also called solutions.solutions A heterogeneous mixture is a mixture where the individual substances remain distinct.heterogeneous mixture Section 3.3 – Mixtures of Matter

10. Separati ng Mixtures Filtration is a technique that uses a porous barrier to separate a solid from a liquid in a heterogeneous mixture.Filtration Distillation is a separation technique for homogeneous mixtures that is based on the differences in boiling points of substances.Distillation Crystallization is a separation technique for homogenous mixtures that results in the formation of pure solid particles from a solution containing the dissolved substance.Crystallization Sublimation is the process of a solid changing directly to a gas, which can be used to separate mixtures of solids when one sublimates and the other does not.Sublimation Chromatography is a technique that separates the components of a mixture on the basis of tendency of each to travel across the surface of another material.Chromatography

End of Section 3.3

11. Elements Section Elements & Compounds An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.element 92 elements occur naturally on Earth. Each element has a unique name and a one, two, or three- letter symbol. The periodic table organizes the elements into a grid of horizontal rows called periods and vertical columns called groups.periodic table Elements in the same group have similar chemical and physical properties The table is called “periodic” because the pattern of similar properties repeats

12. Compounds A compound is a made up of two or more elements combined chemically.compound Most of the matter in the universe exists as compounds. Table salt, NaCl, and water, H 2 O, are compounds. Elements can never be separated. Compounds can be broken into components by chemical means. The properties of a compound are different from its component elements. This figure shows electrolysis of water to form hydrogen and oxygen.

13. Law of Definite Proportions The law of definite proportions states that a compound is always composed of the same elements in the same proportion by mass, no matter how large or small the sample.law of definite proportions Joseph Proust (France 1799) The relative amounts are expressed as percent by mass, the ratio of the mass of each element to the total mass of the compound expressed as a percentage.percent by mass Example: H 2 O is always made up of 2 atoms of H and one atom of O. The ratio of O to H in water is always 16:2 or 8:1. This table demonstrates that the percentages of elements in sucrose remain the same despite differences in sample amount.

14. Law of Multiple Proportions The law of multiple proportions states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in whole number ratios.law of multiple proportions –H 2 O 2 and H 2 O –Copper(I) chloride and copper(II) chloride

Law of Multiple Proportions (cont.) Practice Problem 1: In the carbon compounds ethane (C2H6) and ethane (C2H4), what is the lowest whole number ratio of H atoms that react with the same number of C atoms? Answer: 3:2 Practice Problem 2: Carbon reacts with oxygen to form two compounds as shown: Compound A: 2.41 g C, 3.22 g O Compound B: 6.71 g C, 17.9 g O Find the lowest whole number ratio of C that reacts with an equal mass of O Answer: 2:1

Law of Multiple Proportions (cont.) Practice Problem 3: Lead forms two compounds with oxygen as shown: Compound A: 2.98 g Pb, g O Compound B: 9.89 g Pb, g O For a given mass of oxygen, what is the lowest whole number mass ratio of lead in the two compounds? Answer: 1:2

End of Section 3-4

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