Chapter 1 Structure and Bonding

Question 1

What is an atom

Answer 1

an atom consists of a dense, positively charged nucleus surrounded at a relatively large distance by negatively charged electrons.

Question 2

What is a nucleus

Answer 2

Nucleus consists of subatomic particles called neutrons, which are electrically neutral, and protons, which are positively charged.

Question 3

Atomic Number (Z)

Answer 3

Gives the number of protons or an atom contains.

Question 4

Mass number (A)

Answer 4

which gives the total number of protons and neutrons in its nucleus.

Question 5

Isotopes

Answer 5

Atoms with the same atomic number but different mass numbers are called? Neutrons can change.

Question 6

Atomic Weight

Answer 6

The weighted-average of an element’s naturally occurring isotopes is called…..

Question 7

Node

Answer 7

A region of zero electron density around the nucleus.

Question 8

Atomic Orbital

Answer 8

A mathematically defined 3D region of space around a nucleus where an electron spends its time.

Question 9

Electron Cloud

Answer 9

made from electrons relatively small and contain 1- charge, determines volume of an atom.

Question 10

Electron shell

Answer 10

The orbitals in an atom are organized into different layers around the nucleus called….

Question 11

Aufbau principle

Answer 11

The lowest-energy orbitals fill up first, 1S->2S->2P->3S

Question 12

Pauli exclusion principle

Answer 12

Only two electrons can occupy an orbital, and they must have opposite spins.

Question 13

Hund’s Rule

Answer 13

If two or more empty orbitals of equal energy are available, one electron occupies each with spins parallel until all orbitals are half-full.

Question 14

Covalent bond

Answer 14

shared electron bond not by gaining or losing electrons, but by sharing them.

Question 15

Molecule

Answer 15

The neutral collection of atoms held together by covalent bonds.

Question 16

Lewis structures/ Electron-dot structures

Answer 16

the valence-shell electrons of an atom are represented as dots. A stable molecule results whenever a noble-gas configuration of eight dots and octet is achieved.

Question 17

Kekule structures/ line-bond structures

Answer 17

two-electron covalent bonds are indicated as lines drawn between atoms.

Question 18

Lone-pair electrons/ nonbonding electrons

Answer 18

Valence electrons that are not used for bonding remain as dots in structures are called….

Question 19

Valence bond theory

Answer 19

a covalent bond forms when two atoms approach each other closely and a singly occupied orbital on one atom overlaps a singly occupied orbital on the other atom.

Question 20

Sigma Bonds (σ)

Answer 20

Bonds which are formed by the head-on overlap of two atomic orbitals along a line drawn between the neclei. Increased electron density in middle between atoms.

Question 21

Molecular Orbitals

Answer 21

mathmatical combination of atomic orbitals that forms so e- belong to the whole molecule.

Question 22

sp^3 orbitals

Answer 22

One 2s+3p form four new sp^3 orbitals to make for new sigma bonds. First bond between atoms is always a sigma bond and allows for free rotation. Tetrahedral geometry with 109.5 bond angles.

Question 23

sp^2 hybridization

Answer 23

one 2s+two 2p= three new sp2 orbitals. 3 sigma bond and one pi bond can be made. trigonal planar geometry with 120 bond angles.

Question 24

Pi bonds (π)

Answer 24

result from sideways overlap, relatively weak bonds, do not allow for free rotation, Pi bonds is every bond other than sigma bonds.

Question 25

Sp Hybridization

Answer 25

One 2s+one 2p= two new sp orbitals. uses two sp to make 2 sigma bonds two unchanged p orbitals used to make 2 pi bonds, linear molecule with 180 bond angles.

Question 26

Ground state electron configuration

Answer 26

assigning electrons to the proper orbitals, beginning with the lowest-energy ones