Name ______Date______Hr______

Notes – Atoms & the Periodic Table

Q: What’s an atom?

  • The ______that still has all ______

______

______

  • EX.
  • Brownian motion
  • Named after Robert Brown (Scottish botanist).

Q: What does an atom look like?

  • An atom is ______
  • Atoms have a ______ at their center
  • Atoms contain what we call ______.
  • 3 subatomic particles:
  • Electron ( )
  • Location-
  • Charge –
  • Relative Mass-
  • Proton ( )
  • Location-
  • Charge –
  • Relative Mass-
  • Neutron ( )
  • Location-
  • Charge –
  • Relative Mass-

Draw a picture of an atom below. Label each of the three subatomic particles, as well as the nucleus and electron cloud.

Q: What is the overall charge of the nucleus in an atom? Why?

Each type of atom has a different number of p+, e-, and n0. We can use the Periodic Table to determine how many of each an atom contains.

Q: What is the Periodic Table?

  • Where we can look to find ______
  • The table is organized based on ______ such as:

Q: How do I read the periodic table?

  • First, you must realize that each box contains information about

______.

  • The smaller number (usually at the top) represents the ______
  • Tells us how many ______ an atom of that element has
  • Tells us how many ______ an atom of that element has

*** Only if the atom is ______

  • The larger number (usually at the bottom) represents the ______
  • Measured in ______
  • Tells us the total number of ______ present in an atom
  • How can I use this to find just the number of n0?
  • Chemical symbol
  • Usually only ______
  • Some have ______- these are manmade and will likely get renamed.
  • First letter is always ______, second is always ______
  • Some symbols are based on the ______ for the element

Ex.

Example: Find the element Bismuth (Bi) on your PT.

Atomic Number:
Atomic Mass:
Symbol: / # p+ =
# e- =
# n0 =

1. Atomic Number

  • The smaller number with no decimal place
  • Represents/determines the number of protons and electrons present in a neutral atom
  • increase from top to bottom and from left to right
  • If the atomic number is 2, the atom has 2 electrons and 2 protons
  • If the atomic number is 10, that atoms has …
  • i.e.

Potassium

39.098

K

19

  • Potassium has 19 protons and when neutral, 19 electrons.

2. Atomic Mass Number

  • is the larger number with a decimal place and is measured in amu (atomic mass units)
  • This number gives us the number of p + n in an atom
  • To find the number of neutrons, we have a simple formula:
  • Mass number – atomic number

3. Chemical symbol

  • some have single letters – always capitalized
  • some have two letters – first letter always capitalized, second letter is lower-case
  • some have three letters – these are all man-made and may get renamed
  • some symbols are based on Latin words
  • Ex) Aurum – gold – Au Ferrum – iron – Fe
  • Any element with an atomic number greater than 92 is man-made (created in a lab)

Why is there usually a decimal place in the atomic mass number?

  • It is due to isotopes.
  • Isotopes – atoms of the same element with the same # of protons but a different # of neutrons
  • the mass number is an estimate of all of the possible isotopes of each element
  • example: 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 12.011, which is closer to 12 than 14

How is the periodic table divided?

Into Metals, Nonmetals and Metalloids or into Families and Periods (Rows/Columns).

Types

1. Metals

  • are located to the left of the zigzag (exceptions: H and metalloids)
  • properties include:
  • have luster (shine)
  • can be stretched and shaped
  • conduct heat and electricity very well

2. Nonmetals

  • are located to the right of the zigzag (exceptions: metalloids)
  • Properties include:
  • dull
  • poor conductors of heat and electricity

3. Metalloids/Semi-metals/Semi-conductors

  • along the zigzag (B, Si, Ge, As, Sb, Te, Po)
  • Properties include:
  • some are shiny, some are dull
  • not as good of conductors as metals but better conductors than nonmetals

Families Vs. Periods (Rows versus Columns)

1. Rows/Periods

  • are called periods
  • are horizontal (side to side)
  • elements in the same row/period DO NOT have common properties
  • there are 7 of them on the periodic table

2. Columns/Groups

  • are called groups or families
  • are vertical (up and down)
  • elements in the same group/family DO have common properties
  • there are 18 of them on the periodic table
  • Ex) 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.
  • Elements in the same group/family have the same number of valence electrons
  • Valence electrons – the number of electrons in an atom’s outermost energy level
  • Ex) argon (Ar) versus neon (Ne)
  • Atoms want to achieve a filled outermost energy level – we call this an “octet” if the energy level contains 8 valence electrons.

Are the groups named?

  • Eachfamily of elements group has its own name.

Families

Alkali metals

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

Alkaline Earth metals

  • Group 2 elements
  • Have 2 valence electrons
  • Less reactive than alkali metals but are still reactive
  • Tend to react with group 6 elements

Transition metals

  • group 3-12 on periodic table
  • those families that we did not number
  • Metals, but different from alkali or alkaline earth metals
  • Most have 1 or 2 valence electrons
  • Includes mercury (Hg) – the only liquid metal at room temperature

Halogens

  • Group 7 elements
  • Some are gases, Br is liquid, and some are solids
  • Have 7 valence electrons
  • Tend to react with group 1 elements (alkali metals)

Noble gases

  • Group 8 elements
  • He has 2 valence electrons
  • Ne, Ar, Kr, Xe, Rn all have 8 valence electrons
  • Are not reactive since they already achieved an “octet”
  • Contribute to less than 1% of earth’s atmosphere
  • O2 (21%) and N2 (78%) contribute to most of the atmosphere.

***Rare-Earth Elements

  • includes elements at bottom of periodic table (periods 6 and 7)
  • first row = lanthanoid series- tend to be metals
  • second row = actinoid series – most are manmade (transuranium elements) and radioactive

Names and symbols

  • You will become familiar with the most commonly used elements and their symbols

Name Symbol

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Aluminum Al

BoronB

CalciumCa

CarbonC

ChlorineCl

CopperCu

HeliumHe

HydrogenH

IronFe

NitrogenN

Oxygen O

SodiumNa

GoldAu

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Bohr Model

  • We can use the periodic table to draw Bohr Models. These are also referred to as planetary models.
  • In these models we represent the protons, neutrons, & all the electrons.
  • We already know that protons and neutrons are located in the nucleus at the center.
  • The electrons are located in the electron cloud in energy levels
  • 1st level holds max 2
  • 2nd 8e-
  • 3rd 18e-
  • 2n^2
  • Fill in the following diagram: (done w/ students in class)

Lewis (Dot) Diagrams:

  • Electron dot diagrams are structures that show the valence electrons as dots
  • Valence electrons are the electrons in the outmost shell and can be determined by looking at the group number on the periodic table
  • Groups IA – 8A (SKIP THE TRANSITION METALS)
  • If an element is in group IA it has 1 electron in its valence shell.
  • If an element is in group VA, it has 5 electrons in the valence shell, and so on…
  • To draw the diagram:
  • Write the symbol down
  • Place dots around the symbol, one on each side and then begin to pair them

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