CHM 2045C Kotz6e Text

Chapter 1: Matter and Measurement

Key Terms

1.* Absolute zero: the lowest temperature believed to be possible. It is defined to be zero kelvin and has a value on the Celsius scale of -273.15E C.

2.* Accuracy: the agreement of a measurement with the accepted value for the quantity.

3. Atom: the smallest particle of an element that retains the characteristic chemical properties of that element.

4. Boiling point: the temperature at which a liquid boils.

5. Chemical bond: an interaction between two atoms that holds them together in a molecule, ionic crystal, or covalent network.

6. Chemical change: a change that produces one or more new substances.

7. Chemical formula: a listing of the chemical symbols for the elements present in a compound and the relative number of atoms of each element present (written as subscripts).

8. Chemical property: a characteristic of a material that describes whether and sometimes how readily one material will react with another material.

9. Chemical symbol: an abbreviation used to represent an element.

10.* Density: indicates how much matter is packed into a given space; mathematical it is calculated by dividing the mass of a material by its volume (D = m/V).

11.* Dimensional analysis: a technique that pays attention to the units in a calculation. The units are treated like factors that can be cancelled if the appear both in the numerator and denominator of a calculation.

12. Ductility: the ability of a material to drawn into wire.

13. Electric conductivity: a property that indicates whether a material will conduct electricity and the extent to which it can do so.

14. Extensive property: a property of a substance that depends on the amount of the substance present.

15. Gas: the physical state of matter that has neither a fixed volume nor a fixed shape – both the volume and shape of a gas is determined by its container. The volume of a gas varies with temperature and pressure.

16. Heterogeneous: not uniform throughout.

17. Homogeneous: uniform throughout.

18. Intensive property: a property of a substance that does not depend on the amount of the substance present.

19. Ion: an electrically charged atom or group of atoms.

20. Kinetic energy: the energy of motion.

21. Kinetic Molecular theory: a theory of matter used to explain the properties of solids, liquids, and gases. This theory supposes that all matter consist of extremely small particles (atoms, molecules, or ion) which are in constant motion.

22. Liquid: the physical state of matter with a volume that changes little as temperature and pressure change but that has no definite shape of its own – a liquid takes on the shape of the portion of the container that it fills.

23. Macroscopic: large-scale; the macroscopic view in chemistry is the world in which we live and make observations.

24. Malleability: the ability of a material to be deformed (bent).

25. Matter: anything that mass and takes up space.

26. Melting point: the temperature at a which a solid melts.

27. Mixture: a material formed by physically together to or more elements, two or more compounds, or a combination of elements or compounds. A mixture can be made using any relative amounts of the components. The components do not chemical bond to each other in the mixture.

28. Molecule: the smallest particle found in nature for those elements whose atoms chemically bond together to form small discrete particles; also, the smallest discrete particle of a nonionic compound.

29. Periodic table: a table that lists the elements in order of increasing atomic number and places elements with similar properties in the same vertical column. Each box on the periodic table usually includes the symbol for an element as well as other useful information about the element.

30. Physical change: a change in physical properties; a physical change does not produce new substances.

31. Physical property: a characteristic of a material that can be observed without changing the composition of a substance.

32.* Precision: indicates how well several determinations of the same quantity agree.

33. Pure substance: a material that has its own set of unique properties and that cannot be separated into two or more different species by and physical technique.

34.* Pyrometer: a device used to measure temperature; it measures the wavelength of light emitted from an object and relates that to the object’s temperature.

35. Qualitative observation: an observation that does not involve measurements and numbers.

36. Quantitative observation: an observation that involves numerical information.

37.* SI: the Système International d’Unitès, the modern incarnation of the metric system used in scientific work.

38.* Significant figures: the digits in a measured quantity that are know exactly plus one digit that has some uncertainty; in the answer to a calculation, one should report only digits that are significant.

39. Solid: the physical state of matter that has a rigid shape and a fixed volume that changes little as temperature and pressure change.

40. Solubility: the amount of a material that will dissolve in a given amount of another material

41. Solution: a homogeneous mixture in which the components are evenly distributed in each other down to an atomic or molecular scale.

42. Submicroscopic (particulate): the level of matter dealing with atoms, molecules, and ions.

43.* Temperature: a property that determines the direction of heat transfer; heat transfers from something at a higher temperature to something at a lower temperature.

44.* Viscosity: a measure of how easily a liquid flows; the more viscous a liquid is, the less readily it flows.

* Key Terms which are introduced in Module 2 and will not be tested in Module 1 Part K.