U2

describe the bonding in metals

"sea of electrons" -delocalized electrons which are free to move through the positive metal ion

How many electrons are involved when two atoms in a molecule are connected by a double bond? Triple bond?

4 electrons for double bond 6 electrons for triple bond

matter

anything that has mass

What type of bonding involves the sharing (either equally or unequally) of electrons between atoms? What type of atoms usually make this type of bond?

covalent - non metals only

Explain how the atoms in covalent molecules achieve configurations similar to those of the noble gases. How does this differ from the situation in ionic compounds?

covalent molecules; atoms (nonmetals) share e- to fill valence orbitals (s & p) ionic compounds; metals transfer e- to nonmetals, so each will have full valence orbitals

types of chem bonds

covalent, ionic, metallic

Why are the valence electrons of an atom the only electrons likely to be involved in bonding to other atoms?

e- in full energy levels (core e-) do not need to gain or lose e- to have full orbitals. Only valence orbitals need to gain or lose e- to achieve a noble gas configuration.

valence electrons

electrons in the outer most energy level of an atom; s and p orbital

compare and contrast ionic and covalent

ionic - metal and nonmetal, transfer of electron. covalent - nonmetals, share electron. both - both bonds involve valence electrons, both make molecule that's more stable

when do ionic bonds form

ionic bonds form when atoms are held together by the attraction between opposite charges

what type of bonding requires the complete transfer of an electron from one atom to another? what type of atoms usually make this type of bond?

ionic metals with nonmetals

distillation

liquid is boiled to produce a vapor. vapor is then condensed into liquid - method of seperation for 2 or more liquids with boiling points greater than 25C difference

atoms of element

made up of subatomic particles of that element

law of conservation of mass

mass is conserved in any physical or chemical change

chunky peanut butter

mixture, heterogeneous

pepsi

mixture, heterogeneous

Gasoline

mixture, homogeneous

bronze

mixture, homogeneous

tap water

mixture, homogeneous

molecule

neutral group of atoms joined together by covalent bonds - can be diamotic or compound ;A group of atoms bonded together

polar vs nonpolar

polar is unequal sharing of electrons, nonpolar is equal sharing of electrons

filration

process to separate a solid from a liquid (separate a heterogeneous mixture - called filrate)

magnesium chloride

pure sub, compound

diamond

pure sub, element

lithium

pure sub, element

distilled water

pure, compound

element

simplest form of matter with unique set of properties

atom

smallest particle of an element retains its identity in chem reaction

compound

sub made up of 2 or more different elements chemically combined in a fixed porportion

reactant

substance present at the start of reaction

product

substance produced in a reaction

molecule of element

2 or more of same type of atom chemically bonded together

What does it mean to say that a bond is polar?

A bond is polar when the shared e- are closer to one of the bonded atoms (due to that atom having a larger electronegativity value).

alloy

A mixture composed of 2 or more elements, at least one of which is a metal.

heterogeneous mixture

A mixture that is not uniform in composition; components are not evenly distributed throughout the mixture

electrolysis

A process by which electrical energy is used to bring about chemical change

In a lab, students are asked to determine the relative amounts of benzoic acid and charcoal in a solid mixture. Benzoic acid is soluble in hot water, but charcoal is not. Devise a method for separating the two components of this mixture.

Add hot water to the sample. This will dissolve the benzoic acid but not the charcoal. The hot sample can be filtered through filter paper, which will remove the charcoal (it will stay in the filter paper) while the solution of benzoic acid will go through the filter paper. Allow the solution to cool so that the benzoic acid will crystallize back out. Then the benzoic acid can be filtered out. Allow both components to dry and then find their masses.

How can we show the dipole moment of a polar bond?

An arrow drawn next to the bond with the arrow head pointing toward the partial negative end or a low case delta symbol with a + or -.

Although both the BF3 and NF3 molecules contain the same number of atoms, the BF3 molecule is flat whereas the NF3 molecule is trigonal pyramidal. Explain.

BF3 has 3 e- areas (3 bonded & zero lone pairs) so the molecule is flat (2-D) - trigonal planar. NF3 has 4 areas of e- (3 bonded & 1 lone pair) - the lone pair of e- givens the molecule a tetrahedral electronic shape and also makes the molecular shape be 3-D (the lone pair created the point of the pyramid)

Pure substance X is melted, and the liquid is placed in an electrolysis apparatus. When an electric current is passed through the liquid, a brown solid forms in one chamber and a white solid forms in the other chamber. Is substance X a compound or an element? Explain your answer.

Compound; two different solids form from one substance.

physical properties

a quality or condition of a substance that can be observed or measured without changing the substance's composition

describe how the process of distillation could be used to separate a solution into its component substances.

Distillation can be used when the components of a mixture have different boiling points. Salt water; by boiling a solution of salt water, the water would boil off first leaving the salt behind. (Water has a lower boiling point than table salt.)

What do chemists mean by the term electronegativity?

Electronegativity is the relative ability of an atom in a molecule to attract shared e- to itself.

What is the geometric structure of the water molecule? How many pairs of valence electrons are there on the oxygen atom in the water molecule? What is the approximate H-O-H bond angle in water?

Electronic structure = tetrahedral, molecular structure = bent, 2 lone pairs & 2 bonded pairs of e-, 109 ̊

What is the geometric structure of the CH4 molecule? How many pairs of valence electrons are present on the carbon atom of CH4? What are the approximate H-C-H bond angles in CH4?

Electronic structure = tetrahedral, molecular structure = tetrahedral, 0 lone pairs & 4 bonded pairs of e-, 109

What is the geometric structure of the ammonia molecule? How many pairs of electrons surround the nitrogen atom in NH3? What is the approximate H-N-H bond angle in ammonia?

Electronic structure = tetrahedral, molecular structure = trigonal pyramid, 1 lone pair & 3 bonded pairs of e-, 109 ̊

What is the geometric structure of the boron triflouride molecule, BF3? How many pairs of valence electrons are present on the boron atom in BF3? What are the approximate F-B-F bond angles in BF3?

Electronic structure = trigonal planar, molecular structure = trigonal planar, 0 lone pairs & 3 bonded pairs of e- 120 ̊

describe how the process of filtration could be used to separate a mixture into its components

Filtration can be used when the components of a mixture have different solubilities in water. A mixture of sand and salt; when adding water to the mixture, the salt will dissolve and the sand will not. When you pour the mixture through filter paper, the sand will stay in the filter paper while the salt water will go on through.

Does the fact that a molecule posses polar bonds mean that the molecule itself will also be polar?

If the dipole moments of each bond cancel out (due to strength and shape of the molecule) then the molecule is nonpolar.

Mixture

a physical blend of two or more substances that are not chemically combined

Explain (on the particulate level) how metals conduct electricity.

The delocalized electrons are free to move around the positively charged metal ions.

What are the conditions that give rise to a bond's being polar?

The greater the electronegativity difference, the more polar the bond.

What does its electronegativity tell us about the atom?

The larger the electronegativity value, the closer the shared e- tend to be to that atom when it forms a bond.

Explain how the valence shell electron pair repulsion theory (VSEPR) is used to predict the arrangement of the electron pairs about the central atom.

The structure around a given atom is determined by minimizing repulsion between e- pairs.

physical change

a change during which some properties of a material change, but the composition of the material does not change

chemical change/reaction

a change that produces matter with a different composition - one or more new/different substances formed

what is a chemical bond

a force that holds groups of 2 or more atoms together

homogeneous mixture (solution)

a mixture that is uniformed in composition; components are evenly distributed and not easily distinguished

chemical properties

the ability of a substance to undergo a specific chemical change

what does It mean to say that a compound always has to same composition

the molecules of that compound always contain the same type and number atoms

what are valence electrons only electrons involved in bonding

they are the electrons that come in contact with eachother first when 2 atoms come near eachother

pure substance

uniform and definite composition (all one element, all one molecule, or all one compound)

When do covalent bonds form?

when atoms share electrons in order to satisfy the octet rule

when predicting formula for ionic compound

write the charges for both then swap the charge Ba+2----F-1= BaF2 (2 goes down) don't write a charge