Chapter 4: Atoms

Flip Me Over

Ok, so I’m too lazy to type these up, but ya gotta know the first 36 elements and their symbols and whatnot AND also Ag, Au, Pb, Hg, I

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okie dokie? okie dokie.

Elements

Pure substances from which all other things are build

* Made up of 1 atom
* Cannot be broken down further

Chemical Symbols

Represent the names of the elements

* Consist of 2 symbols
* One uppercase, one lowercase

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\*spelling counts\*

What is Zn?

Aluminum or Aluminium?

Flourine or Fluorine?

Zinc

Aluminum

Fluorine

Periodic Table

Organizes 118 elements into groups with similar properties and places them in order of increasing atomic number

Groups

Contain elements with similar properties in vertical columns

* Also called families

Periods

Horizontal rows of elements counted from top to bottom as periods 1-7

How are groups labeled?

**Old Naming:**

* A = representative elements (Main Group)
* First 2, and Last 6
* B = transition elements
* 10 in the Center

**New Naming:**

* All columns are labeled left to right 1-18

What are the sections and families of the period table?

1A (1) = Alkali Metals

2A (2) = Alkaline Earth Metals

The Bs (3-12) = Transition Metals

7A (17) = Halogens

8A (18) = Noble Gasses

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Hydrogen = bro’s weird, has its own section

Alkali Metals

Extremely reactive

* Stored in oil bc water will make them react

**Group 1A**

* Lithium (Li)
* Sodium (Na)
* Potassium (K)
* Rubidium (Rb)
* Cesium (Cs)

\*as you go down the list, the reactivity increases\*

Alkaline Earth Metals

Shiny + not as reactive as 1A

* Used in fireworks!

**Group 2A**

* Beryllium (Be)
* Magnesium (Mg)
* Calcium (Ca)
* Strontium (Sr)
* Barium (Ba)
* Radium (Ra)

Halogens

Toxic, smell bad, reactive and form compounds with most of the elements

* Especially with 1A

**Group 7A**

* Fluorine (F)
* Chlorine (Cl)
* Bromine (Br)
* Iodine (I)

Heavy Zigzag

Separates nonmetals and metals

* **Metals:** on the left
* **Non-Metals:** on the right
* **Metalloid:** along the zigzag (not alumnium)

Metals

* Shiny
* Ductile (ability to be pulled into wires)
* Conduct heat and electricity
* Solid at room temp (except Mercury)
* High densities and melting points

Why is hydrogen not included with the metals?

It displays more traits of nonmetals

Nonmetals

* Dull
* Brittle (becomes powder if tried to pull)
* Poor conductors
* Good insulators
* Low densities and melting points

Metalloids

* Exhibit properties of both metals and nonmetals
* Better conductors than nonmetals but not as good as metals
* Used as semi-conductors and insulators
* They can be modified to function as conductors or insulators
* Batteries, paints, ceramics, etc.

Atom

Smallest part of an element that maintains the characteristics of that element

What was Dalton’s Atomic Theory also influenced by?

The Law of Conservation of Mass

Dalton’s Atomic Theory

1. Atoms are tiny particles of matter
2. Atoms of one element are similar to each other and different from those of other elements
3. Atoms of two or more different elements combine to form compounds
4. Atoms are rearranged to form new combinations in a chemical reaction

What are the subatomic particles and what are their charges?

Protons = positive; p⁺

Electrons = negative; e⁻

Neutrons = neutral; n⁰

Like charges _____ , unlike charges ______

Like charges *repel*, unlike charges *attract*

Atoms are always neutral: True or False

True; elements and atoms are not the same, atoms must always be neutral

J.J. Thomson’s Cathode Ray

* Realized that cathode rays contain negatively charged particles


* Particles (now called electrons) have a much smaller mass than the atom

What did J.J. Thomson propse?

A “plum pudding“ model; electrons were scattered randomly through a positively charged space

* No knowledge of protons; just that there was positive charges

Rutherford’s gold foil

→ wanted to figure out how much space electrons took up

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Positively charged particles were aimed at atoms of gold

* Mostly went straight through, deflected only occasionally
* Concluded that there must be a small, dense, positively charged nucleus that deflected the positive particles that came close to the nucleus

Atomic Structure

* Nucleus in the center w/ protons and neutrons
* Electrons that occupied the large empty space around the nucleus

Where is most of the mass of an atom?

The nucleus

Atomic Number

Appears above the symbol

* Same for every atom of that element
* The number of protons
* A whole number

What does net 0 mean and what does that describe about the subatomic particles?

Net 0 = neutral

* Same amount of protons and electrons

Mass Number

Located under the symbol

* Not on our given periodic table :<
* Represents the number of particles in the nucleus (protons and neutrons)

Isotopes

Different atoms of the same element

* Have different mass numbers
* The same number of protons, different number of neutrons
* Can be distinguished by their atomic number

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²⁴Mg = the 24 is the mass

Do all isotopes occur in the same percentage?

Nope; they have varying ranges of occurrence

Formula for Calculating Atomic Mass of multiple Isotopes

For each isotope: Mass(amu) x percent abundance/100

Add up all the values (don’t forget sig figs)

If you are given ⁶L and ⁷L and the mass given on the periodic table is 6.941 amu, which isotope is more abundant?

Since the 6 and 7 in ⁶L and ⁷L represent the mass, and the value we are given is 6.941, we need to figure out which value is closer.

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The more abundant something is, the more it will appear overall, it’s the same principle with numbers. Meaning, we can use 6 and 7 as a range and since 6.941 is closer to 7, we can assume that ***⁷L is more abundant***

Electromagnetic Radiation

Consists of energy particles that move as waves of energy

* In different forms such as light, rainbow, x-ray

Distance between the peaks of waves

Wavelength

High-energy radiation has _____ wavelengths and low-energy has ______ wavelengths

High-energy radiation has *short* wavelengths and low-energy has *long* wavelengths

Electromagnetic Spectrum: Low to High

Radio, Microwave, Infrared, Visible Light (ROYGBIV), UV, X-Ray, Gamma

What’s the different between a red and blue wavelength?

**Red:** shorter wavelength

**Blue:** long wavelength

Atomic Spectrum

When light from a heated element passes through a prism, it separates into distinct lines of color separated by dark areas that are called an atomic emission spectrum

What is the use of an atomic spectrum?

Each element has its own distinct emission spectrum

* Helps with identification

What are the lines in an atomic spectrum associated with?

The changes in the energies of the electrons

Energy level

The specific energy of an electron in an atom

How are energy levels labeled?

They are assigned a principal quantum number represented with the letter n.

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n = 1, n = 2…

What happens when you add light energy to an atom?

First, the atoms is at its ground state. Once energy is added, the atom absorbs it and get excited and jumps to a further energy level(the more energy, the farther the energy level). However, the atom doesn’t like this unstable state and returns to its original ground state.

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When the atom returns to its ground state, energy is released back in light form. This energy emitted is equal to the difference between the two energy levels the atom traveled between.

Sublevels

The arrangement of electrons that determines the physical and chemical properties of an element

Where are sublevels located?

In energy levels

How can you determine the amount of sublevels within an energy level?

The # of sublevels is equal to the principal quantum number of that energy level

What are the 4 different sublevels in ascending order?

s

What would the sublevels in an n = 3 energy level be?

s, p, and d

Organize the following in order (largest to smallest)

* Electrons
* Energy levels
* Sublevels
* Orbitals

Energy levels, sublevels, orbitals, electrons

How many electrons fit in an orbital and how are they arranged?

2

one up and one down

How many orbitals does each sublevel have and how many electrons can the entire thing hold??

s → 1 orbital = 2 electrons

p → 3 orbitals = 6 electrons

d → 5 orbitals = 10 electrons

f → 7 orbitals = 14 electrons

Orbital

A three-dimensional volume in which electrons have the highest probability of being found

* Location of an electron describe in terms of probability (electron cloud)

S orbitals

Shown as spheres

* Increase in size as n increases

What would an s orbital be called?

1s or any number based on its n value

P orbitals

Two lobes; like a ballon tied in the middle

* The three p orbitals are arranged perpendicular to each other along the x, y, and z axes around the nucleus
* Each piece is along a different axis

What are the names of the p orbital parts? (in n = 2)

2px, 2py, 2pz

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The extra letter represents the direction

D orbitals

Four of the five d orbitals consist of 4 lobes that are aligned along of between different axes.

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The fifth consists of two lobes (like a p orbital) with a doughnut-shaped ring around its center

What are the names of the d orbital parts?

dxy, dyz, dxz, dx²-y², dz²

The Pauli Expulsion Principal

* Each orbital can hold a max of two electrons
* Electrons in the same orbital repel each other
* Electrons in the same orbital must have their magnetic spins cancel (they spin in opposite directions)

What are the rules of drawing orbital diagrams?

1. Fill the orbitals and energy level from lowest to highest energy level
2. Each orbital holds 2 electrons max
3. Fill orbitals within the same sublevel one at a time before pairing electrons

Orbital order

1s2s2p3s3p4s3d4p5s4d5p

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No commas

Use of electron configuration

* Indicate placement of electrons
* Show how electrons fill energy levels and sublevels in order of increasing energy

What can you do with really long electron configurations?

Write an abbreviated version using a noble gas

* Go up one row and down to the noble gas
* Put that noble gas in brackets and write the rest of the electron configuration

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ex. SODIUM = \[Ne\] 3s¹

What must you do with Helium when doing electron configurations?

Move it next to Hydrogen

Valence Electrons

In the outermost shell and are responsible for the chemistry and reactions

Valence Electron Configurations

The group # of s and p blocks tell you the # of outermost electrons

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8A = 8 valence electrons

Octet Rule

8 = stability

Sublevel sections of the periodic table

First two = s

Last 6 = p

Transition metals = d

Bottom two rows = f

Lewis Symbols

Display valence electrons

How to draw Lewis Symbols

Draw electrons as dots in pairs

* Go around the entire 4 sides AND THEN start to pair

Trends in the periodic table

Atomic Size and Metallic Character decrease left to right

Ionization Energy increases left to right

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Atomic Size and Metallic Character increase top to bottom

Ionization Energy decreases top to bottom

Atomic Size

Affected by the attraction between the protons in the nucleus and the electrons in the outermost energy level

* More protons = stronger attraction that brings the electrons closer = smaller overall size
* Basically the radius

Ionization Energy

Energy needed to loose electron

* If more protons are present, it will be more difficult to kick out electrons
* When the space between the protons and electrons expand, as it does going down, the electrons are easier to kick out

What does it mean to ionize?

Loose an electron

Metallic Character

Ability to loose electrons easily

* Metals have more metallic character, so as you go down the metals, they want to loose their electrons
* As you go further towards the halogens, they want to gain the electrons and bond

What does this mean?

* The energy of an electron is quantized

Electrons can have only specific energy values

What increases as the n # increases

* Why?

The energy

* The electrons are further away from the nucleus meaning the positive protons cannot combat its energy