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Chemistry is a Physical Science

Chapter 1, Sections 1 and 2. Chemistry is a Physical Science. Introduction. Chemistry: the study of the composition, structure and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes

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Chemistry is a Physical Science

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  1. Chapter 1, Sections 1 and 2 Chemistry is a Physical Science

  2. Introduction • Chemistry: the study of the composition, structure and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes • There are six branches of chemistry to deal with the main areas of study • The branches often overlap

  3. Branches of Chemistry • Organic chemistry: the study of most carbon-containing compounds • Inorganic chemistry: the study of non-organic substances, many of which have organic fragments bonded to metals • Physical chemistry: the study of the properties and changes of matter and their relation to energy

  4. Branches of Chemistry • Analytical chemistry: the identification of the components and composition of materials • Biochemistry: the study of substances and processes occurring in living things • Theoretical chemistry: the use of mathematics and computers to understand the principles behind observed chemical behavior and to design and predict the properties of new compounds

  5. Matter • Mass: a measure of how much matter you have • Matter: anything that occupies space and has mass • Two main types of matter: mixture and pure substance

  6. States of Matter • Solid: has a definite volume and definite shape • Liquid: has a definite volume but an indefinite shape (assumes the shape of the container) • Gas: no definite volume or shape (assumes the shape of the entire container) • Plasma: high-temperature physical state of matter in which atoms lose most of their electrons

  7. Visual Representations

  8. Atoms • Atom: all substances are made up of atoms • Atoms are the smallest particles present in an element and still remain the element • Elements contain only one type of atom • Elements are found on the periodic table • Atoms can join together by chemical bonds to form compounds

  9. Molecules • Molecule: a small group of atoms joined together by covalent bonds • If the atoms are different, you have a molecule of a compound • If the atoms are the same, you have a molecule of an element • Most elements that are gases at room temperature are diatomic

  10. HON and the Halogens • Hydrogen (H), oxygen (O), nitrogen (N), and the halogens (fluorine, chlorine, bromine, and iodine) are diatomic in all physical states when not bonded (H2, O2, N2, F2, Cl2, Br2, I2)

  11. Visual of Molecules

  12. Types of Properties • Extensive properties: depend on the amount of matter that is present Examples include: volume, mass, amount of energy in a substance • Intensive properties: do not depend on the amount of matter present Examples include: melting and boiling point, density, ability to conduct electricity and transfer heat

  13. Visual of Types of Properties

  14. Properties • Physical properties: properties that can be observed and measured without changing the material's composition • Examples would be color, density, melting point, boiling point • Chemical properties: properties that can only be observed by changing the composition of the material • Examples: reactivity, ability to burn, acidity, decompose

  15. Changes • Chemical change: changes the chemical properties of the substance, you will have new substance(s) with new properties • A chemical change is the result of a chemical reaction • Physical change: does not change the chemical properties of the substance, usually changes its state of matter or size (as in cutting into smaller pieces)

  16. Changes • Reactants: the substances that react in a chemical change • Products: the substances that are formed by the chemical change • NaHCO3 + HClNaCl + H2O + CO2 • reactants products

  17. Evidence of a Chemical Change • Color change ( could just be dissolving, but is also evidence of a chemical change) • Formation of a precipitate (solid product) • Formation of a gas, usually evidenced by bubbles in a liquid • Energy change (products become hotter or colder, light or sound is produced) • The only way to know for sure is that you have a new substance

  18. Mixture • Different substances are not combined chemically • Can be separated by physical means • Ratio of the components is not constant • Its properties are similar to those of its components

  19. Types of Mixtures • Homogeneous mixture • uniform in composition • AKA solution • Heterogeneous mixture • Not uniform throughout • Can usually see the different components

  20. To Separate a Mixture • Pick out the big pieces • Use of a magnet (solid from a solid) • Filtration, decant, centrifuge (liquid from a precipitate) • Paper chromatography (liquid from a liquid) • Distillation (liquid from a liquid)

  21. Pick Out the Big Pieces • Use forceps or tweezers • Pick out the pieces you want and put in a separate container • Label the container

  22. Use of a Magnet • Pass the magnet through the mixture completely • Remove the magnet • Scrape off the substance • Place in a labeled container

  23. Filtration • Fold the filter paper • Insert in the funnel • Pour the liquid/solidmixture into the funnel • Allow to filter completely • Remove the filter paper and allow it to dry

  24. Decant • Allow the mixture to separate • Carefully pour off the top layer only • Place in a separate labeled container

  25. Centrifuge • Place the substance in a centrifuge tube • Place in a balanced centrifuge • Run the centrifuge • Remove the sample and decant • Place in a separate labeled container

  26. Paper Chromatography • Spot the paper with the mixture • Place in a container with solvent • Allow the mixture to separate

  27. Distillation • Used to separate two liquids • Heat in the distillation apparatus • Allow the liquid to separate according to boiling point • Place the liquid in a labeled container

  28. Pure Substances • Can not be separated by physical means • All samples have identical chemical properties • Are further divided into elements and compounds • Elements can not be split up into simpler substances by chemical means, compounds can

  29. Compounds • Made up of different types of atoms chemically bonded together • The constituent elements will be in fixed proportions and will have different properties than the compound • Can only be separated into its elements by a chemical change • The chemical change will break some bonds and form new ones which results in a new substance

  30. mixture pure substance pure substance mixture pure substance pure substance mixture

  31. Types of Atoms • 92 kinds of atoms (elements) that occur naturally • More have been produced artificially • Each element has a symbol • You should know the symbols and the spelling for the elements used frequently

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