1. What are the three subatomic particles and their charges?
September 22 Bellwork
What are the three subatomic particles and their charges?

2. What is an Atom?
The smallest particle of matter that still has all of the properties and characteristics of that type of matter.
A copper atom is the smallest particle of copper that still has all properties of copper.

3. Brownian motion – the perpetual movement of particles (jiggling atoms) named after Robert Brown (Scottish Botanist)

4. What Do Atoms Look Like?
An atom is mostly empty space and contains what we call subatomic particles. They are electrons, protons and neutrons.

5. Subatomic Particles
Protons with a positive charge found in the nucleus of an atom
Neutrons with a neutral charge also found in the nucleus of an atom
Electrons with a negative charge found outside of the nucleus in the electron cloud

6. The Periodic Table
The elements are arranged according to characteristics in a grid-like structure, both how they look as well as the way they act
Each box represents an element and each box contains the
Atomic number (number of protons/electrons)
Atomic mass number
Chemical symbol

7. Atomic Number The smaller number with no decimals
Represents the number of protons and electrons in a neutral atom
Periodic trend: increases from top to bottom and from left to right
Example: If the atomic number is 2, then the atom has 2 electrons and 2 protons.
Example 2: K has _19_ protons and _19_ electrons when neutral

8. Atomic Mass Number The larger number with a decimal
Measured in amu (atomic mass units)
Represents the number of protons and neutrons in an atom
Atomic Mass # = protons + neutrons

9. Therefore… To find the number of neutrons:
Neutrons = mass number – atomic number

10. Example Carbon has a mass number of 12.011 and an atomic number of 6.
How many protons does it have?

11. Chemical Symbol Single letters or first letter capitalized
If there are 3 letters, it is a man-made element that may get renamed
Gold – Au (aurum)
Iron – Fe (ferrum)

12. Any element with an atomic number greater than 92 is man- made

13. Isotopes
Atoms of the same element with the same number of protons but different number of neutrons
The mass number is an estimate of all of the possible isotopes of each element
Isotopes are the reason that there is usually a decimal point in the atomic mass number

14. Example of an Isotope C-12 has 6 neutrons, C-14 has 8 neutrons
C-12 is more often found in nature, so the atomic mass of C is which is closer to 12 than 14

15. How the Periodic Table is Set up
Metals, Nonmetals, Metalloids
Families (rows) and Periods (columns)

16. Metals
Located to the left of the zigzag (except hydrogen and metalloids)
Properties:
Luster (shine)
Can be stretched and shaped
Good conductors of heat/electricity

18. Nonmetals Located to the right of the zigzag Properties: Dull
Poor conductors of heat/electricity

20. Metalloids/Semi-metals/Semi-conductors
Along the zigzag: B, Si, Ge, As, Te, Po
Properties:
Some are shiny but some are dull
Not as good of conductors as metals but better than nonmetals

22. Periods (Rows) and Families (Columns)
Rows/Periods
Horizontal
Elements in the same period don’t have the same properties
7 on the periodic table

23. Periods (Rows) and Families (Columns)
Columns/Families
Also called groups
Vertical
Elements in the same group/family have common properties
18 on the periodic table

24. Li, Na, K all have a similar chemical reaction with water (H2O)
They all create an explosion that releases hydrogen gas (H2)
Therefore, they are stored with oil, not water.

25. Valence Electrons
The number of electrons in an atom’s outermost energy level
Elements in the same group/family have the same number of valence electrons

26. Atoms want to achieve a filled outermost energy level
we call this an “octet” if the energy level contains 8 valence electrons

27. Each Family of Elements Has its Own Name
Alkali Metals
Alkaline Earth Metals
Transition Metals
Halogens
Noble Gases

28. Alkali Metals Group 1 elements (except H) Have 1 valence electron
Are the most active metals
Tend to react with group 7 elements (halogens)

29. Alkaline Earth Metals Group 2 elements Have 2 valence electrons
Less reactive than alkali metals but still reactive
Tend to react with group 6

30. Transition Metals Groups 3-12 on periodic table
Metals, but different from alkali
or alkaline earth metals
Most have 1 or 2 valence e-s
Include mercury (Hg) – the only
liquid metal at room temperature

31. Halogens Group 7 elements
Some are gas, Br is liquid, and some are solid
Have 7 valence e-s
Tend to react with group 1 elements (alkali metals)

32. Noble Gases Group 8 elements Helium has 2 valence e-s
Ne, Ar, Kr, Xe, Rn, all have 8 valence e-s
Are not reactive since they already achieved an octet
Make up less than 1% of earth’s atmosphere
Oxygen (21%), nitrogen (78%) contribute to most of the atmosphere

33. Rare-Earth Elements
Includes elements at bottom of periodic table (periods 6&7)
First row = lanthanoid series (tend to be metals)
Second row = actinoid series (most are man-made and radioactive)

35. Names and Symbols of Commonly Used Elements
Aluminum (Al)
Boron (B)
Calcium (Ca)
Carbon ( C )
Chlorine (Cl)
Copper (Cu)
Helium (He)
Hydrogen (H)
Iron (Fe)
Nitrogen (N)
Oxygen (O)
Sodium (Na)
Gold (Au)

36. We Can Use the Periodic Table to Draw Bohr Models
A.k.a “planetary models”
Protons, neutrons and electrons are represented in the Bohr Model
We know that protons and neutrons are located in the nucleus at the center
The electrons are located in the electron cloud in energy levels

37. Energy Levels 1st level holds a max of 2 e-
2nd level holds a max of 8 e-
3rd level also holds 18 e-

38. Lewis (Dot) Diagrams
Electron dot diagrams are structures that show the valence electrons as dots
Valence electrons are the electrons in the outermost shell and can be determined by looking at the group number on the periodic table
Groups 1A – 8A (SKIP TRANS. METALS)

39. If an element is in group 1A it has 1 V. E
If an element is in group 1A it has 1 V.E. If an element is in group 5A is has 5 V.E.

40. Drawing Lewis Diagrams
To draw the diagram:
Write the symbol down
Place dots around the symbol, one on each side and then begin to pair them

41. Ions and Isotopes
Isotopes: atoms of the same element with the same #p+ but different # of neutrons
Mass Number: whole number; is only for one isotope of an atom
Atomic mass: has decimal places because it is an average of the masses of all of the isotopes

42. Ions An atom or molecule that has a charge.
Loss of electrons  Positive charge (cation)
Gain of electrons  Negative charge (anion)

43. What is different between the 3 isotopes of hydrogen?

44. Isotopes
Isotopes= atoms of the same element that have the same atomic number but different atomic masses due to a different number of neutrons.

45. Protons and neutrons have a relative mass of 1, and electrons are 1/1840, so electrons don’t really count when determining the mass.
•Since most of the mass of the element is from protons and neutrons, changing the number of neutrons changes the mass of the atom.
•To determine the atomic mass, scientists take an average mass of al isotopes of that atom. This gives us decimal places.

46. Example of an Isotope Carbon-12 has a mass number of 12
•How many protons does it have? Why?
•How many electrons does it have? Why?
•How many neutrons does it have? Why?

47. Example 2 Carbon-14 has a mass number of 14
•How many protons does it have? Why?
•How many electrons does it have? Why?
•How many neutrons does it have? Why?

48. When scientists take the average of these masses to determine the atomic mass, they also consider which is more abundant (common) in nature.
C-12 is more often found in nature so the atomic mass of C is , which is closer to 12 than 14.

49. What happens if we don’t have the same number of protons and electrons?
Then we no longer have a neutral atom!
–Neutral atoms have NO charge
–They have the same number of positive particles as negative particles. (They cancel each other out).

50. Neutral Atom Example: –Oxygen has an atomic number of 8.
–An atom of oxygen has 8p+ and 8e-
–So = 0

51. Ions
In order for an atom to not be neutral, the number of electrons changes but the number of protons and neutrons stays the same
Ion – atom with either a positive or negative charge (a charged particle)

52. O-2 Neutral vs ion atom Formula: electrons = protons – charge
Neutrons = 8
Electrons = 8
Protons = 8
Neutrons = 8
Electrons = 10
Formula: electrons = protons – charge
e = 8 – (-2)
Write the ion as either O2- or O-2

53. B+3 Boron ion Protons = Electrons = Neutrons =
Formula: protons – charge = electrons

54. If an atom has 7 protons and 10 electrons, what is its charge?
•Negative ions are called ANIONS
•Positive ions are called CATIONS
Formula 1: Electrons = protons –charge
Formula 2: Charge = protons – electrons

55. Atomic Mass Units (amu)
Today it is possible to determine the mass of an element using a mass spectrometer.
However, numbers are small and impractical to work with. (i.e. Mass of F= x g)
It is easier to use relative masses of atoms using a reference isotope as a standard.

56. Atomic Mass Units
The reference isotope= Carbon 12. This isotope is assigned a mass of exactly 12 amu.
Atomic mass units= 1/12 of the mass of a Carbon-12 atom.

57. Atomic Mass
In nature, most elements occur as a mixture of two or more isotopes.
Atomic mass= the weighted average mass of the atoms in a naturally occurring samples of the element.
Takes into account the relative abundance

59. Atomic Mass
To determine atomic mass, you must know the number of isotopes, the mass of each isotope and the percent abundance of each isotope.
Atomic mass = multiply the mass of each isotopes by natural abundance and add the products.

60. Atomic Mass of Carbon
Example: Carbon has 2 isotopes: Carbon-12 which has a natural abundance of 98.89% (0.9889) and Carbon-13 which has a natural abundance of 1.11% (0.0111).
Atomic Mass of carbon=

61. Atomic Mass of Magnesium
Magnesium has three naturally occurring isotopes % of Magnesium atoms exist as Magnesium-24 ( g/mol), 10.03% exist as Magnesium-25 ( g/mol) and 11.17% exist as Magnesium-26 ( g/mol). What is the average atomic mass of Magnesium?
Atomic Mass of Magnesium=

62. Atomic Mass of Lithium
What is the average atomic mass of Lithium if 7.42% exists as Li-6 (6.015 g/mol) and 92.58% exists as Li-7 (7.016 g/mol)?
Atomic Mass of Lithium=