Properties of Matter Chapter 2 Wrap-up

Matter is anything that has mass and takes up space (has volume). Matter can either be classified as being a pure substance or a mixture. Pure substances contain the same type of matter throughout by having a fixed, uniform composition.

Pure substances can be classified as either being: Elements or Compounds.

Elements An element is a substance that cannot be broken down into simpler substances. organized on the periodic table Fixed composition because it contains only one type of atom An atom is the smallest part of an element and retains all of the properties from the element of which it comes from.

Symbols for elements Each symbol has one or two letters; the first letter of every element symbol is always capitalized. Originally, the symbols were chosen based on the Latin names for the known elements. Ex: Gold’s Latin name is Aurum (Au).

Compounds A compound is a substance made from simpler substances (elements) that are joined (in a chemical bond) together in a fixed proportion. Ex: water (H2O), carbon dioxide (CO2), ammonia (NH3)

Mixtures A mixture contains two or more substances that are not combined chemically The properties of a mixture can vary because the composition of a mixture is not fixed. There are two types of mixtures: heterogeneous and homogeneous

Heterogeneous Mixtures Least mixed mixture Parts of the mixture are easily identifiable.

Homogenous Mixtures appears the same throughout Particles are spread evenly throughout and are not distinguishable best mixed mixture Ex. A solution Kool-aid

Mixtures

Suspensions, Colloids and Solutions Classified based on the size of the largest particles A suspension has the largest particles of the three; large particles scatter light (they do not allow for light to pass through). A suspension is a heterogeneous mixture. EX: soil and water mixed A suspension will separate into layers over time. EX: “Shake well before serving”

Colloids intermediate (medium-sized) particles also scatter light EX: fog and homogenized milk Like solutions, particles of a colloid cannot be separated using a filter and they do not settle into layers over time.

Solutions A solution has the smallest particles of the three; the particles are too small to see with the naked eye. A solution is a homogeneous mixture. Remember: kool-aid!

Physical Properties describe an object; such as, color, odor, size, shape, texture & can be observed without changing the identity of the substance Some are reversible (freezing water, melting ice, braiding hair, wrinkling clothes) Some are not reversible (cutting paper, slicing a tomato, peeling an orange, cutting hair)

Density = Mass ÷ volume or D=m/V Physical Properties Volume: amount of space an object takes up Density: calculated (physical) property of matter that measures the amount of mass per volume. Density = Mass ÷ volume or D=m/V Density can be used to identify specific types of matter. Density does not vary for pure substances.

More physical properties Viscosity: resistance to flowing; (ex. chocolate syrup, pudding) Conductivity: a materials ability to allow heat to flow; metals have high conductivity. Malleability: the ability of matter to be hammered without shattering; also a characteristic of most metals (ex. Gold)

Hardness: a comparison of one material scraping and leaving a mark on the other. Melting point: temperature at which a substance changes from a ________ to a _________. Boiling point: temperature at which a substance changes from a ________ to a _________. solid liquid liquid gas

Using properties to separate mixtures Filtration: a process that uses the size of particles to separate them from a mixture. Distillation: a method of separating parts of a mixture based on the boiling points of those parts.

Chemical Properties the ability to produce a change in the composition of matter Flammability: the ability of a substance to burn in the presence of oxygen Reactivity: the ability of a substance to combine chemically with other substances

Three signs that a chemical change has occurred: 1. Color change 2. Formation of a gas 3. Formation of a precipitate (solid that forms and separates from a liquid mixture)

PSc.2.1 Understand types, properties, and structure of matter. PSc.2.1.1 Classify matter as: homogeneous or heterogeneous; pure substance or mixture; element or compound; metals, nonmetals or metalloids; solution, colloid or suspension. PSc.2.1.2 Explain the phases of matter and the physical changes that matter undergoes. PSc.2.1.3 Compare physical and chemical properties of various types of matter.