Atoms

Vocabulary  Atomic #  Proton  Neutron  Electron  Isotopes  Mass #  Model

Protons, neutrons, and electrons

Nucleus-the central part of the atom, is made from protons and neutrons.

What is the atomic # What is floating around the nucleus? What particles make up nucleus?

MODELING ATOMS Because atoms are so small, scientists create models to describe them. Models may be a diagram, mental picture, mathematical statement, or an object that helps explain ideas about the natural world

Identifying Numbers  Atomic number- the number of protons in the nucleus of an atom  Atomic Mass-the number of protons and neutrons in the nucleus of an atom.

Number of Neutrons  Isotopes-are atoms of the same element that have different numbers of neutrons.  Ex-Carbon-12, Carbon-13 and Carbon- 14

Carbon Isotopes  Carbon-12 has 6 protons, 6 neutrons, and 6 electrons  Carbon-13 has 6 protons,, 7 neutrons, and 6 electrons  Carbon-14 has 6 protons, 8 neutrons, and 6 electrons.

Use of radioactive isotopes  Isotopes are used in the medical field  Ex-Iodine-131 is used to diagnose thyroid problems. It is injected into the patient and shows up in x-rays as it goes through the body.  Isotopes are also used in the environment. These are placed in fertilizers, pesticides etc.

Strong Nuclear Force  The force that holds protons together in the nucleus of an atom.  This force is what keeps the positive force of protons from pushing each other apart. This works because the protons are packed so tightly together.

Radioactive Decay  The release of nuclear particles and energy from an atom.  Only unstable atoms-atoms with a different number of neutrons than protons, undergo radioactive decay.  The changing on one element into another through radioactive decay is transmutation.

Vocabulary  Atomic mass  Periodic table  Chemical symbol  Period  group

Patterns in the Elements 63 elements discover in 1869, Mendeleev discovered a set of patterns that applied to all the elements Mendeleev’s work Atomic mass= average mass of all isotopes for that element He noticed pattern as he arranged the elements by the increasing atomic mass Mendeleev's Periodic table Found properties repeated and he placed them in groups together Predicting new elements Found arrangement by mass did not always group them by similar characteristics Left blank spaces for undiscovered elements Published in 1869 first table

Modern periodic table Periodic table- chart of the elements showing the repeating pattern of the chemicals and the properties Period-a row (periodic means regular repeating pattern) Rearranged by atomic # Finding Elements Square (key) includes the atomic #, symbol, Atomic mass, and name Atomic Number (#) Tells you the number of protons

Chemical symbols and names Contains either one upper case letter (K) or one upper case and a lower case (Na) taken from their Latin names Average Atomic mass The last number in key is an average because most elements have isotopes and it is the combined percentage of all of their weights Organization of the Periodic Table Arranged by atomic number Properties of an element may be predicted from its location on the table Periods7 horizontal rows (like the days of the week) Groups18 Vertical columns, known as families, have similar characteristics

Section 2  Mendeleev- Discovered elements had a pattern to their properties when he arranged them by increasing atomic mass.  He formed the first periodic table  Left blanks and predicted that new elements would fill those spots

Today’s table  Properties of elements may be predicted by their placement on the periodic table.  Arranged by atomic number  18 columns called groups/families have similar characteristics  7 rows called periods

Atomic Mass  Average of all the atomic weight of the isotopes and the elements  This is why it is a decimal number and not whole #

Definitions  Atomic mass  Periodic table  Chemical symbol  Period  Group

Valence  Notes from movie- valence electrons- ones in the outer shell  Orbital and electron shells same

Now let’s talk more about electrons and where they are found!!!!

Electrons are part of what makes an atom an atom atom But where exactly are the electrons inside an atom?

Orbitals are areas within atoms where there is a high probability of finding electrons.

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Let’s say you have a room with marbles in it The marbles are not just anywhere in the room. They are inside boxes in the room.

You know where the boxes are, and you know the marbles are inside the boxes, but… you don’t know exactly where the marbles are inside the boxes

The room is an atom The marbles are electrons The boxes are orbitals

The room is an atom The marbles are electrons The boxes are orbitals Science has determined where the orbitals are inside an atom, but it is never known precisely where the electrons are inside the orbitals

An interesting place where electrons have a specific organization within atoms, allowing for interesting atom interactions

An interesting place where electrons have a specific organization within atoms, allowing for interesting atom interactions Not an interesting place, where electrons have no specific organization within atoms, where atoms wander aimlessly about (does not actually exist)

The Periodic Table

Characteristics of Metal  Malleable—a material that can be hammered or rolled, coins (ex. Gold, magnesium, aluminum)  Ductile—a material that can be pulled out, wire  (ex. Gold, magnesium, aluminum)  Conductivity—ability to transfer heat or electricity  Luster- shiny  Octet rule—states that atoms tend to combine in such a way that they each have eight electrons in their valence shells

Alkali Metals  Alkali metals—Group 1, the alkali metals are all highly reactive and are never found in elemental forms in nature, one electron in their outmost electron shells Alkali metals—Group 1, the alkali metals are all highly reactive and are never found in elemental forms in nature, one electron in their outmost electron shells

Alkaline Earth Metals  Alkaline earth metals—Group 2, insoluble in water and resistant to heating, two electrons in their valence shell f726TgczA&edufilter=DQBPVNZ5nlf NZmzO0OgIrQ

Transition Metals  Transition metals—Groups 3-12, characteristics include hard and shiny, good conductors

Earth Metals  Earth metals—Group below the steps, not very reactive

Metalloids  Metalloids—along the border between metals and nonmetals, have characteristics of both

Boron Family Boron family -- Group 13. This group includes the elements All five have three electrons in their outer energy level.

Carbon Group  Carbon group—Group 14, can gain, lose, or share electrons

Nitrogen group  Nitrogen group—Group 15, can gain or share three electrons, noted for their stability in compounds, this is the property of these elements which leads to their potential toxicity

Oxygen Group  Oxygen—Group 16, can gain or share two electrons

Halogens  Halogens—Group 17, can gain or share one electron, very reactive, forms salts  Nonmetals

Noble Gases  Noble gases—Group 18, odorless, colorless, with very low chemical reactivity, full valence electron shells  nonmetals

Below the Table  Lanthanides—Top row, soft, malleable, shiny metals with high conductivity, used for alloy (mixture of metals)  Actinides—Bottom row, very unstable  Synthetic Elements—any elements with an atomic number higher than 92

Ionic Bond  ~between metals & nonmetals ~electrons are TRANSFERRED from the metal to the nonmetal making ions ~electrons are TRANSFERRED from the metal to the nonmetal making ions  Giving electrons makes one positive  Taking electrons makes one neagative ~Ex. NaCl (sodium gives 1 electron to chlorine; then making Na+ and Cl -) ~Ex. NaCl (sodium gives 1 electron to chlorine; then making Na+ and Cl -)

Ions  Formed when electrons (-) are given away from metal resulting in a positive charge, because the number of protons (+) is greater than the number of electrons (-) in the atom  Positive ions are called cations

Ions  Formed when electrons (-) are received from an element (nonmetal) resulting in a negative charge, because the number of protons (+) is less than the number of electrons (-) in the atom  Negative ions are called anions.

Explanatory videos  8Jhhpc&edufilter=DQBPVNZ5nlfNZmzO 0OgIrQ 8Jhhpc&edufilter=DQBPVNZ5nlfNZmzO 0OgIrQ 8Jhhpc&edufilter=DQBPVNZ5nlfNZmzO 0OgIrQ  edLuRmw&edufilter=DQBPVNZ5nlfNZm zO0OgIrQ

Covalent Bonding  ~usually between nonmetals ~electrons are SHARED ~electrons are SHARED ~Ex. H2O (2 hydrogen atoms share electrons with 1 oxygen atom) ~Ex. H2O (2 hydrogen atoms share electrons with 1 oxygen atom)

COVALENT BOND bonds formed by the sharing of electrons

Covalent Bond  Between 2 nonmetallic elements of similar electronegativity.  Formed by sharing electron pairs  Examples; O 2, CO 2, C 2 H 6, H 2 O, SiC