1. Chapter 4 Earth Chemistry

2. Be sure to also review atomic particles
And the periodic table

3. Chapter 4:1 Matter
                               

5. Objectives
Compare chemical properties and physical properties of matter
Describe the basic structure of the atom
Compare atomic number, mass number, and atomic mass
Define isotope
Describe the arrangement of elements in the periodic table

6. What is matter? Matter is anything that takes up space and has mass.
Amount of matter is the mass of an object
Observable and measurable properties

8. Element
A substance that cannot be broken down into a simpler form by ordinary chemical means.

9. Primary Earth Elements

10. Bohr_s_Model_of_the_Atom

11. Atom
Is now defined as the smallest particle of an element that retains the chemical properties of that element. Made of subatomic particles
Electrons
have a negative charge
Nucleus
Protons –
positive charge
and
Neutrons -
neutral charge

12. Electron Cloud
Electrons do not orbit around the nucleus like miniature planets… instead they are found in “clouds” or regions of probability around the nucleus.
Electrons

13. Atomic Number
Each kind of atom has its own distinct atomic number. Only atoms of that element have the same atomic number.
Atomic number equals number of protons
Uncharged atom – equal number of protons and electrons, atomic number = number of electrons
For Example GOLD, has a atomic number of 79. Gold has 79 protons in its nucleus. No atoms have an atomic number of 79 except GOLD atoms.

14. Exploring_the_Modern_Periodic_Table

15. Two_Rows_of_Elements_at_Bottom_of_Periodic_Table

16. Periodic Table of Elements
Elements in same column have similar arrangement of electrons

17. Using_the_Modern_Periodic_Table

19. Atomic Mass
The mass number of any atom is the TOTAL number of protons AND neutrons in the nucleus of an atom.
For example GOLD, has a mass number of 197 amu or atomic mass units.

20. Isotopes
Atoms of the same element (the same number of protons) with different numbers of neutrons. They have identical atomic numbers but different mass numbers.

21. ISOTOPES
Different number of neutrons / different masses yields isotopes of same element with different properties

23. Average Atomic Mass
Weighted average of the atomic masses of naturally occurring isotopes of an element
Average calculated for Periodic Table

24. Valence Electrons
Similarities in chemical properties places elements in periodic table in columns or groups
Outermost electrons in cloud are Valence
Atoms’ number of valence electrons generally same for every atom in that group

25. Metals and Nonmetals
Elements whose atoms with only 1, 2, or 3 valence electrons lose electrons easily
Metallic properties and classified as metals
Elements whose atoms ranging from 4-7 valence electrons more likely to gain electrons
Classified as nonmetals

26. Families__Alkali_Metals__Halogens__Noble_Gases_

27. Section 4.2 Combinations of Atoms

28. Section Objectives Define compound and molecule.
Interpret chemical formulas.
Describe two ways that electrons form chemical bonds between atoms.
Explain the differences between compounds and mixtures.

29. Elements_and_Compounds

30. Compound
A substance that is made of two or more elements that are joined by chemical bonds.
The compound’s properties differ from those of the elements that compose it.

31. Molecule
The simplest unit of a compound that retains all of the substances chemical properties.

32. Diatomic Molecule
Molecules made up of two atoms, which can be the same element.
N2, F2, Cl2, O2.

33. Chemical Formulas
A combination of symbols and numbers that show which elements, and the number of atoms of each element, that make up a molecule of a compound. The numbers here are called subscripts.
How about (NH4)2CO3?

34. Chemical Equations
A formula that describes the chemical reaction of elements and compounds to form new compounds.

35. Equation Structure reactants → products
The arrow means “gives” or “yields”.
For the picture, the chemical equation is:
2H2 + O2 → 2H2O

36. Balanced Equations
The number of atoms of each type must be equal to each other on either side of the arrow.
You cannot change the chemical formulas.
We put numbers (called coefficients) in front of the reactants or products to make it balance.

37. So, Let’s Balance This Puppy!
CaCO3 + HCl → Ca2+ + Cl− + CO2 + H2O
CaCO3 + 2HCl → Ca2+ + 2Cl− + CO2 + H2O

38. Chemical Bonds The forces that hold atoms together in a molecule.
Produced by the sharing or transferring of electrons from the outermost (valence) electrons of two or more atoms.

39. Ions
An atom or group of atoms that carries an electrical charge from either gaining or losing an electron(s), trying to fill the valence shell and “look” like a noble gas.
Gain = negative charge
Loss = positive charge

40. Ionic Bond
The attractive force between oppositely charged ions that result from the transfer of electrons.

41. Ionic Compound A compound formed through the transfer of electrons.
MOST are formed by the transfer of electrons from a metal to a non-metal.
Example: NaCl (table salt)

42. Covalent Bond
A bond based on the attraction between atoms that SHARE electrons.

43. Covalent Compound
A compound formed by the sharing of electrons by two or more atoms. Each atom “thinks” that it “looks” like a noble gas.
Diatomic Hydrogen

44. Polar Covalent Bonds
Chemical bonds are rarely PURELY ionic or covalent, they are usually somewhat “in between”, and the atoms do not share the electrons equally.

45. Metallic Bonds (Not In The Book)

46. Metals_and_Non_Metals

47. Mixture
A combination of two or more substances that are not chemically combined.
A mixture (unlike a compound) can be physically separated into its individual parts.

48. Heterogeneous Mixtures
Where two or more substances are not uniformly distributed.
Granite, mostly a mixture
of orthoclase and quartz.

49. Homogenous Mixtures
Means “having the same composition and properties throughout.”
Also called a solution, in which two or more substances are uniformly dispersed.
Can be solid, liquid, or gas.
Smog build-up during the day

50. Alloy A solution composed of two or more metals.
For example, this 15th century bronze door is made up of a SOLID solution of copper and tin…BRONZE

51. Assignment
4.2 Key Terms
Directed Reading