Chemistry MYP 1 Advanced

Modern Atomic Theory All matter is composed of atoms. Atoms can’t be subdivided, created or destroyed in ORDINARY chemical reactions. It is possible with nuclear reactions. Atoms of an element have a mass that is unique to that specific element. Atoms of any one element have properties that differ from other elements.

What’s in an atom? Atoms are neutral There are protons, which have a positive charge. Electrons which have a negative charge. Neutrons that have no charge. These are found in the nucleus of the atom. The mass of an atom is made up of the protons and the neutrons. The nucleus is small and dense.

Atomic Number The number of protons in the nucleus of an element

Atomic Mass The number of protons and neutrons in the nucleus of the element.

The Bohr Model of the Atom Neils Bohr imagined that electrons orbited the nucleus like planets orbited the sun.

Electron Energy Level

Electron Orbitals An orbital is a region within an energy level where there is a probability of finding an electron. Orbital shapes are defined as the surface that contains 90% of the total electron possibility. The S orbital has a spherical shape The P orbitals are dumbbell shaped The D orbitals are double dumbbell shaped

Electron Orbitals and Energy Levels

Periodic Table of the Elements

Periodic Table of the Elements The groups are arranged in columns and the periods are arranged in rows

Alkali Metals They are in group 1 They all have one valence electron They are never found pure in nature because they are too reactive. As you go down the group the reactivity increases.

Alkaline Earth Metals They have 2 valence electrons Less reactive than alkali metals They are the 2nd group in the periodic table They are not found pure in nature because they are too reactive

Properties of Metals Good conductors of heat and electricity Malleable Ductile High Tensile Strength Luster

Transition Metals All of the metals in the middle section of the periodic table Includes gold and silver

Properties of Metalloids Properties of metals and non metals More brittle than metals but less brittle than non metals Semiconductors of electricity

Nonmetals Poor conductors of electricity Brittle Gases at room temperature Ex: Carbon

Halogens The group before last They have 7 valence electrons Never found pure in nature because they are too reactive They must be diatomic molecules to be found pure Ex. Cholorine

Noble Gases 8 valence electrons; except helium it has 2 Only found pure in nature and are not reactive Colorless and odorless They were the last of the elements to be found.

Valence Electrons The electrons that sit in the last energy level that are available for bonding.

The Periodic Table and Valence Electrons Group 1 has one valence electron Group 2 has 2 valence electrons available for bonding Group 13 has 3 Valence electrons available for bonding Group 14 has 4 valence electrons available Group 15 has 5 valence electrons Group 16 has 6 valence electrons Group 17 has 7 valence electrons Group 18 has 8 valence electrons that are not available to share. Transition Elements have 1-2 valence electrons Lanthanides (f block) also have 1-2 valence electrons

Bonds Forces that hold groups of atoms together and make them function as a unit. Ionic bonds give up electrons Covalent bonds share electrons

Ionic Bonds Cation is a positively charged ion Anions are negatively charged ions This happens because in Ionic Bonds atoms give up or gain electrons in order to fill their outer energy shell Metals tend to lose electrons to become positively charged Nonmetals tend to gain electrons to become negatively charged. When writing ionic formulas you need to write them with the charges and make sure that they are a balanced. When you name ionic compounds the cation goes first and then the anion. The anion normally will end in the suffix -ide

Covalent Bond One of the strongest bonds. Electrons are shared. Only involved in nonmetals The term molecule is exclusively used for covalent bonding They follow the same rules about satisfying the need to fill the last electron shell. Fluorine will give it up to anyone. When writing or representing them bonds can be represented by dots : or with dashes – Hydrogens and Halogens form one covalent bond Oxygen and Sulfur form 2 covalent bonds ( either 1 double bond or 2 single bonds) Nitrogen and Phosphorus form 3 covalent bonds (either 1 triple, 2 double and 1 single, or 3 single bonds) Carbon and silicon form 4 covalent bonds

Lewis Structures for Covalent Bonds

Forming Covalent Bonds