elements, compounds and mixtures元素，化合物和混合物

1、Elements, compounds and mixtures,,What is an element?,,An element is…,material made of just one type of atomA substance that can not be separated or broken down into simpler substances by chemical means,What are the 3

2、most abundant elements that make up the earth?,,answer,OxygenIronsilicon,Composition of the earth,What are 3 most common elements that make up a human being?,,answer,OxygenCarbonhydrogen,Elements that compose a human

3、 body,What is an Atom?,,atom,The smallest unit of an element that maintains the properties of the element,What is a compound?,,Compound,A substance made of two or more different elements that are combined chemicallyPro

4、perties of compounds may not be the same as properties of elements that make them up,Compounds,Substances composed of 2 or more elements that have been chemically combinedGlassSugarWaterSalt,compounds in real life,M

5、y gold ringWater in a bottleMetal cartCopper wiring,Elements in real life,Neon lights24 Karat gold barOxygen in a scuba tank,What is a molecule?,,Molecule,The smallest amount of a compound that still retains th

6、e qualities of the compound1 molecule of water is composed of 2 hydrogen and 1 oxygen atom,Sugar molecule: Made up of atoms combined in a specific way,Oxygen atoms are red, grayCarbon atoms are whiteHydrogen are sm

7、all white with red dots,Water on a molecular level,Comparisons and contrasts,Element and compoundComparison: Both are pure substancesContrast: Elements can only be composed of one type atom, Compounds are compose

8、d 2 or more types atoms (elements),Atom and Molecule,Comparison: The smallest unit that still retains material’s propertiesContrast: Atom is the smallest unit of an element, Molecule is the smallest unit of a compoun

9、d. Molecules can be composed of different types of atoms,What is a pure substance?,,What does it mean to be a pure substance?,“100% pure Honey”,“100% pure salt or sugar”,Pure substance,Substance composed of either a sin

10、gle type of element or compound chemically combinedIf a Compound, a pure substance has a fixed composition or proportions of elementsevery molecule of water has 2 hydrogen and one oxygen atomAll compounds can be w

11、ritten with a chemical formula,Pure Substance,An amount of matter , either single element or one compound that exhibits distinct chemical and physical propertiesTable Salt (if just made with NaCl) is a pure substance

12、Grape Juice is not (Water, Sugars, Vitamins),What is a mixture?,,Mixture,A combination of 2 or more pure substance combined physicallyClassified by how thoroughly they are mixedProperties of mixture similar to proper

13、ties of components,Mixtures,If you can separate the substances, it’s a mixtureIf it has ingredients, it’s a mixture,Types of Mixtures,HeterogeneousHomogeneousMiscibleImmiscibleAlloy,Heterogeneous mixture,Mixtures w

14、ith ingredients that do not mix well or stay mixed longExamples:Chocolate syrup and milk,Homogeneous Mixture,Mixtures that mix very wellSolutions where substances dissolve well into each otherCan not visually s

15、ee any separation of the ingredientsExamples: Gasoline, Soda,Pure substance and mixtures,Comparison: both are composed of elementsContrast: Pure substance is composed of an element or compound whose composition i

16、s fixed. Mixture is composed of a combination of pure substances whose composition can vary,What is the difference between heterogeneous and homogeneous mixtures?,,Heterogeneous and homogeneous mixtures,Comparisons: bo

17、th mixturesContrast: Heterogeneous materials do not mix well or evenly. They are easily separated. Homogeneous mixtures do mix well and evenly, not easily separated,Difference…,Heterogeneous mixtures: are mixtures

18、 of 2 or more substances that are not completely soluble (bits of each are seen in mixture)Homogeneous mixtures: are mixtures of 2 or more substances that are completely soluble (blend completely, can not tell componen

19、ts),Miscible mixture,Extremely homogeneousDissolves completelyExample: Air,Miscibilitity,How well substances mix togetherThe greater the ability to mix (solubility), the more miscible it is.Oil and water are immi

20、scible (insoluble)Carbon dioxide and water (very soluble),Immiscible mixture,Extremely heterogeneousDon’t mix well at allExamples water and granite,Immiscible Mixture,Gasoline, Soda,Solubility,Measurement of the

21、ability of one substance (solute) to dissolve into another substance (solvent),What is an alloy?,,Alloy,An alloy is a solid homogenous mixture of two or more metals. The there is not chemical reaction occurring, and t