E lements Chapter 4 Section 1

1. Elements Chapter 4 Section 1

2. What are elements? An element is a pure substance that can not 
be separated into simpler substances by 
physical or chemical means.

3. What is a pure substance? A pure substance is a substance in which 
there is only one type of particle. All particles of a pure substance are 
identical.

4. Every element has unique set of properties 
which are used to identify that element. A. Characteristic properties b. Physical pproperties c. Chemical properties

5. 4. Using examples given on  page 83 please complete the following: Cobalt: Melting point:_____________ Density:_________________ Physical properties: _____________________________________________ Chemical properties:  ____________________________________________ Iron: Melting point: ____________________ Density:___________________________ Physical properties:________________________________________________ Chemical properties:_________________________________________________

6. Why are most elements on earth not found 
in their pure form? Because most elements in nature react with 
oxygen and water to form compounds.

7. Iron as used for construction Iron Ore as found in nature Copper Sheet Gold bars Lead casing used to store radioactive elements.

8. How are elements classified? a. Metals b. Non metals c. Metalloids

9. What are metals? They are shiny. They can conduct electricity. Can conduct thermal energy. Malleable which means they can be 
pounded into sheets. Ductile which means they can be drawn into 
wires. Examples:

10. What are metalloids? They are semiconductors. can have both metal and non-metal 
properties. some are shiny and some are dull. can be somewhat mmalleable some can 
conduct heat and electricity. Examples: silicon, boron, antimony

11. 8. What are non metals? Non metals: dull not shiny Poor conductors of heat and electricity when in solid form they are brittle and not malleable few can be used to make various products in their pure form Neon  a gas can be used to create lights Graphite a very soft element is used when making pencils.

12. Graphite as found in nature Graphite centers in pencils

13. Silicon is used in making of computer chips and computer circuits. Boron is used in making old fashioned detergents such as Borax and insect and roach killers. Antimony is used in making materials which can then be used in making of industerial plastic containers.

14. What are compounds? A compound is a pure substance composed 
of two or more elements that are chemically 
combined. Elements must undergo chemical change 
before a compound can be formed.

15. Compound can be simple such as water 
H2o. Compounds can be large and complex such 
as proteins.

16. When compound form elements  join in 
specific ratios according to their atomic 
masses. Water is made of two hydrogens and one 
oxygen at the ratio of 1:8 Hydrogen peroxide is made of two 
hydrogens and two oxygens at the ratio of 
1:16.

17. Carbon dioxide is made of one carbon and 
two oxygen with a ratio of 3:8. Carbon Monoxide is made of one carbon 
and one oxygen at the ratio of 3:4.

18. Every compound has a unique set of 
properties such ad chemical and physical 
properties. These properties are different than the 
properties of the elements that make them.

22. Compounds can be broken down into 
simpler substances through chemical 
change only.

23. Mixtures A combination of two or more substances 
that are not chemically combined.

24. Properties of mixtures 1. Substances in mixtures retain their 
identity. 2. Mixtures can be physically separated. 3. The components of a mixture do not mix 
in a definite ratio.

25. Substances in mixtures retain their identity.

26. Mixtures can be physically separated using A. Distillation B. Use of magnets C. Centrifugation D. Filtertion

27. Distillation of petroleum

28. Desalanation

29. Use of magnets

30. Centrifugation

31. Density Gradient

32. Filteration

33. Solutions Made up of two or more ssubstances appear 
to be one substance because the particles of 
one substance are distributed evenly in the 
other substance

34. Solutions can be made from Two lliquids one liquid and one solid Liquids and gases different gases different solids

35. Solutions are made up of a solute 
and a solvent. Solute dissolves in a solvent.

36. Homogeneous solutions Have the same appearance and properties 
through out The solute completely dissolves in a solvent 
in this type of solution.

37. Heterogenous solutions are made up of 
insoluble salutes which do not dissolve in a 
solvent. This type of mixture is known as a 
suspension.

38. Particles of a solute in a homogeneous 
solution are extremely small vs. the larger 
particles of a suspension. This means that 
light can pass through a solution, but is 
scattered by the particles of a suspension.

39. Concentration A measure of the amount of solute dissolved 
in a solvent. stated in grams of solute per mL of ssolvent 
important for medications

40. Solutions can be: Concentrated dilute Saturated unsaturated

41. Concentrated : has more solute than solvent dilute: has more solvent that ssolute 
saturated: contains all the solute it can hold 
at a given temperature. unsaturated: does not contain all the solute it 
can hold at a given temperature.

43. Solubility refers to the amount of solute 
needed to make a saturated solution using a 
given amount of solvent at a certain 
temperature. It is expressed in grams of solute per 100 
mL of solvent.

44. Solubility is effected by : Mixing heating crushing

45. Mixing: Includes stirring as well as shaking. increases the rate of solubility of a solute in 
a solvent. it helps speed the process of solubility 
because it causes the particles to spread out 
and come into contact with the particles of a 
solvent.

47. Heating Increases the rate solubility for liquid and 
solid solutes in a solvent. Decreases the rate of solubility for gas 
solutes in a solvent.

49. Crushing Increases the rate of solubility for solids by 
creating a higher surface area of solute to 
come into contact with the solvent.