Who devised the model that unified observations about chemical bonding and chemical reactions?
Gilbert N. Lewis and in 1916
What's the octet rule?
the tendency of atoms to react in ways that achieve an outer shell of eight valence electrons is common amongst Group 1A-7A elements.
Atoms with almost eight electrons will...
tend to gain the needed electrons to have eight electrons in its valence shell. Always wants to be a noble gas.
when an atom gains an electron, it becomes...
negatively charged and called an anion.
What about atoms that only have one or two valence electrons?
They tend to lose electrons (to reach noble gas state) They then become positive and positive ions are called cations.
What happens to the number of protons and neutrons in the nucleus of the atom when an ion forms?
remains unchanged; only the number of electrons in the valence shell of the atom changes.
Ions of period 1A and 2A elements with charges greater than +2 are:
unstable.
Can Boron (which has three valence electrons) lose these electrons to become B3+? What about Carbon?
This is far too large a charge for an ion.These changes would place too great a charge on this period 2 Element.
Does the octet rule apply to group 1B-7B elements (transition elements)?
no. Most form ions with two or more different positive charges.
what's monatomic cations and who does it form.
contains only one atom. Forms when a metal loses one or more valence electrons.
which element of groups form only one type of cation?
1A, 2A and 3A. The name of the cation is the name of the metal followed by the word, "ion"
Example:
Group 1A: Hydrogen ion, Lithium ion, Sodium ion...etc.
Group 2A: Magnesium ion, Calcium ion... etc.
Group 3A: Aluminum ion
How do you show the charge in a systematic name?
write Roman numeral (enclosed in parentheses).
Ex: Cu+ is copper(I) ion and Cu+2 is copper(II) ion.
When dos the naming system use -ous and -ic?
Suffix -ous is used to show the smaller charge and -ic is used to show the larger charge.
Looking at Group 1A, 2A and 3A, name all of the cations.
*Say the element with "ion" in the end.
Group 1A: H+, Li+, Na+, K+
Group 2A: Mg2+, Ca2+, Sr2+, Ba2+
Group 3A: Al3+
What are the names of common Monatomic Anions?
Flouride: F-
Chloride: Cl-
Bromide: Br-
Iodide: I-
Oxide: O2-
Sulfide: S2-
What are the names of common polyatomic ions? (Use book btw.)
*Look at book*
What's polyatomic ion?
contains more than one atom.
What are the two major types of chemical bonds? And define.
Ionic:results front he force of electrostatic attraction between a cation and an anion.
Covalent: force of attraction between two atoms that share one or more pairs of electrons. Forms a polyatomic ion.
How can you tell whether two atoms in a compound are bonded by an ionic or a covalent?
1. Consider the positions of the two atoms in the Periodic Table.
2. Ionic bonds form between a metal and a non-mental.
3. Covalent bonds forms between two nonmetals or between a nonmetal and a metalloid.
4. Also, compare the electronagativities of the atoms involved.
What is the electronegativity difference between bonded atoms?
Nonpolar covalent: < .5
Polar covalent: .5 - 1.9
Ionic: 1.9 <
Tetrahedral has ___ regions of electron density around central Atom. The bond angle is ____.
What's the name if it has 1 lone pair, or 2?
4; 109.5*
1 lone pair: Pyramidal Tetrahedral
2 lone pairs: Bent
Trigonal Planar has ___ region of electron density around central Atom. The bond angle is ____.
3; 120*
What's electronegativity? Who devised it? is it a periodic property?
measure of an atom's attraction for the electrons it shares in a chemical bond with another atom. Linus Pauling. Yes.
Electronegativity increases...
why?
left to right; bottom to top across the periodic table.
the number of positive charges in the nucleus of each successive element increases from left to right.
What does ionization energy measure?
the amount of energy necessary to remove an electron from an atom.
How do ionic bonds form?
transferring one or more valence-shell electrons from an atom of lower electronegativity to the valence shell of an atom of higher electronegativity.
The more electronegative atom ____ one ore more valence electrons and become an _____.
The less electronegative atom ____ one ore more valence electrons and become an _____.
1. gains, anion
2. loses, cation.
what is an ionic compound?
compound formed by the electrostatic attraction of positive and negative ions.
A bond is mostly ionic if the electronegativity level is approximately?
What about covalent?
1.9 or greater.
If the difference is less than 1.9.
Since the matter we see around us is electrically neutral... that's means...
the total number of positive charges an ion has must equate the total number of negative charges.
what's a binary compound?
contains only two elements and both elements are presented as ions.
Difference between nonpolar covalent and polar covalent.
nonpolar: electrons are shared equally and for a polar, they are shared unequally.
So... when you find the different between two elements, just look to see if the electrostatic is the same or different.
What's a chemical reaction?
one or more reactants are converted into one or more products.
What does the law of conservation of mass state?
atoms are neither created note destroyed , they just shift from one substance to the other.
What happens during the separation, dissociation?
when ionic compounds, which always consists of positive and negative ions, dissolve in water and the positive and negative ions separate from each other.
What happens when you mix aqueous solutions of two different ionic compounds? Example?
It depends on the ions.
If any of the negative and positive ions come together to form a water-insoluble compound, then a reaction takes place and precipitation takes form.
Ions in solution react with each other only when one of these four things happen:
1. two ions form a solid that is insoluble in water. ex: AgCl
2. two ions form a gas that escapes from the reaction mixture as bubbles.
3. An acid neutralizes a base to form water.
4. One of the ions can oxidize another.
What happens if none of the 4 reactions occur?
Then nothing happens...
Of the four ways for ions to react in water, what is the most common formation?
How can we predict when this result will happen?
Insoluble compound.
If we know the solubilities of the ionic compounds.
What are the usually soluble ionic compounds?
- All group 1A (alkali metal) and ammonium salt.
-All Nitrates
-All common chlorides, bromides and iodides.
-Most sulfates
-All acetates
What are the usually insoluble ionic compounds?
- All phosphates
- All carbonates
- All hydroxides
- All sulfides
What is Oxidation and Reduction?
Oxidation: loss of electrons. The gain of oxygen atoms and loss of hydrogen atoms.
Reduction: gain of electrons. The loss of oxygen atoms and the gain of hydrogen atoms.
What happens in a redox reaction?
The oxidizing agent becomes reduces.
What's an oxidation-reduction reaction?
involves the transfer of electrons from one species to another.
T/F
When Zn is converted to Zn2+, zinc is oxidized.
True.
What is Formula Weight? When is it used?
(FW) the sum of the atomic weights expressed in atomic mass units (amu).
Used for both ionic and covalent compounds.
What is molecular weight and when is molecular weight used?
The sum of the atomic weight of all atoms in the molecular formula expressed in (amu).
used only for covalent compounds.
What's a mole (mol)?
What's the formula called?
amount of substance that contains as many atoms, molecules or ions.
