Chapter 5 Elements, Compounds, Mixtures. Section 1: Elements

Chapter 5

Elements, Compounds, Mixtures

Section 1: Elements

Vocabulary

ElementPure substanceMetalNonmetalMetalloid

Vocabulary

• Element– Substance that cannot be broken down or

be separated into simpler substances by chemical means

• Pure substance– Either an element or a single compound,

that has definite chemical and physical properties

Vocabulary

• Metal – Element that is shiny, – good conductor of heat & electricity

• Non Metal– Does not conduct heat or electricity

• Metalloid– Element with properties of both metal and

nonmetal

Elements, the simplest substance

• Elements are pure• Made of atoms• Each element, only has one type of atom– Silver only has silver atoms in it

• Each atom in an element is identical to each other

Classifying Elements

• Each element is classified by its unique properties– These properties don’t change based

upon the amount of the element• 10 kilograms of silver has the same properties

of 1 milligram of silver

Classifying Elements

• Characteristic properties include both physical and chemical properties– Hardness, melting point, density– Reactivity or flammability

• These properties can be used to identify elements

Grouping Elements

• 3 major groups of elements– Metal– Nonmetal– Metalloid

Grouping Elements

• Metals– Good conductors of heat– Good conductors of electricity– Malleable• Can be shaped

– Ductile• Can be drawn into wires

Grouping Elements

• Nonmetals– Dull• Not shiny

– Poor conductors of heat & electricity– Solids tend to be brittle• Unmalleable

– Few objects made of purely of nonmetals

Grouping Elements

• Metalloids– Semi-metals– Have properties of both metals & nonmetals• some are shiny• Some conduct electricity• Some are dull• Some malleable• Etc….

Section 2: Compounds

Vocabulary

• Compound– Pure substance composed of 2 or more elements

that are chemically combined

Compound: Made of Elements

• Elements combine through chemical changes– Chemical changes mean a new substance– Think water• Hydrogen gas + oxygen gas = water

Compound: Made of Elements

• Chemical changes (reactions) rearrange the atoms– Form in various patterns

• Properties of new substance are different than original atom.

Properties of Compounds

• Compounds have unique properties from the elements that made it

• Always join in specific ratios

Breaking Down Compounds

• Compounds can only be broken by chemical changes– Example --- soda• Carbonic acid is release from the

water/sugar • Creates that fizz–Fizz or bubbles is a sign of chemical

change

Breaking Down Compounds

• Chemical breakdown is harder than physical changes

• Generally energy is needed for a chemical change

Compounds in Your World

• Compounds are everywhere in your world– Industry• Plastics• Metal alloys

– Nature• Water• Sucrose (sugar)

Section 3: Mixtures

Vocabulary

MixtureSolutionSoluteSolventConcentrationSolubility

Vocabulary

• Mixture– Combination of 2 or more substances that

are not chemically combined• Solution– Homogenous mixture• 2 or more substances are evenly dispersed

• Solute– Item to be dissolved

Vocabulary

• Solvent– substance that dissolves the solvent

• Concentration– Amount of a particular substance in a

given quantity of a mixture or solution• Solubility– Ability of a substance to dissolve

Properties of Mixtures

• No chemical changes– So substance still has same chemical make up

• Can be separated by physical method

Properties of Mixtures

• Common Ways to Separate mixtures

– Distillation

– Magnet

– Centrifuge

Properties of Mixtures

• Ratios of particles in a mixture can vary– Remember that in compounds, the ratio is

fixed

Solutions

• Homogenous mixture– Particles are evenly mixed throughout

Solutions

Solutions

• Examples– Soda– Gasoline– Air– Alloys• Mix of 2 or more metals

Concentration of Solution

• Amount of solute in solvent– Normally expressed in grams per milliliter

• Solubility of a solute depends on temperature– Normally higher solubility with higher

temperature