2: Atoms

Question 1

Democritus

Answer 1

All matter is made up of very small particles
Atoms from atomos “not to cut”

Question 2

Element

Answer 2

Substance that consists of identical atoms

Question 3

Compound

Answer 3

Pure substance made up of two or more elements in a fixed ratio by mass

Question 4

ELEMENTS IN THE HUMAN BODY
1. Big Four

Answer 4

C
H
N
O

Question 5

ELEMENTS IN THE HUMAN BODY
2. Next Seven

Answer 5

Ca- strengthens bones; aids blood clotting
P- phosphates of bones, nucleic acids, energy transfer
K- regulate electrical balance of fluids; nerve conduction
S- component of proteins
Cl- necessary for growth and development
Na- regulate electrical balance
Mg- helps nerve and muscle action; present in bones

Question 6

ELEMENTS IN THE HUMAN BODY
3. Trace Elements

Answer 6

Cr
Co
Cu
F
I
Fe
Mn
Mo
Zn

Question 7

Mixture

Answer 7

Combination of two or more pure substances

Question 8

Dalton’s Atomic Theory

Answer 8

1. All matter is made up of tiny indivisible particles, atoms.
2. All atoms of same element have same chemical properties.
3. Compounds are chemical combination of different kinds of atom.
4. Molecule is tightly bound combination of atoms that act as single unit

Question 9

EVIDENCE FOR DALTON’S ATOMIC THEORY
1. Law of Conservation of Mass

Answer 9

-Antoine Lavoisier
-Matter can neither be created nor destroyed.

Question 10

EVIDENCE FOR DALTON’S ATOMIC THEORY
2. Law of Constant Composition

Answer 10

-Joseph Proust
-any compound is always made up of elements in the same proportion by mass

Question 11

Diatomic Elements

Answer 11

H
O
N
Cl
Br
I
F

Question 12

Polyatomic

Answer 12

Ozone, O3
Phosphorus, P4
Diamond, millions of carbon atomd
Etc.

Question 13

Atomic mass unit (amu)

Answer 13

-scale of relative masses of atoms
1 amu= 1.6605x10^(-24)
-mass exactly equal to 1/12 mass of one Carbon12 atom

Question 14

Mass number

Answer 14

number of protons and neutrons in the nucleus of an atom

Question 15

Atomic number

Answer 15

Number of protons in the nucleus of an atom

Question 16

Isotopes

Answer 16

-Same number of protons but different number of neutrons; different atomic mass
-rejects second statement of Dalton’s atomic theory

Question 17

Atomic weight

Answer 17

-Weighted average of the masses of the naturally occurring isotopes of the element
-unit: amu

Question 18

Mendeleev (1860s)

Answer 18

-produced one of the first periodic tables
-arranging known elements according to increasing atomic weight

Question 19

CLASSIFICATION OF METALS
1. Metal

Answer 19

An element that is solid, shiny, conducts electricity, ductile, malleable and forms alloy

Question 20

CLASSIFICATION OF METALS
2. Nonmetal

Answer 20

-Element that does not have the characteristic properties of a metal and tends to accept electrons
-Graphite (form of carbon) is a nonmetal but conducts electricity (only exception)

Question 21

CLASSIFICATION OF METALS
3. Metalloid

Answer 21

Element that displays some of the properties of both metal and nonmetal

Question 22

Niels Bohr (1913)

Answer 22

-only certain values of kinetic energy of electrons are possible (energy levels); values inbetween are not permitted

-electrons in atoms do not move freely in space around nucleus; confined to specific regions called principal energy levels/ shells

Question 23

Ground state electron configuration

Answer 23

The electron configuration of the lowest state of an atom

Question 24

Principal energy level

Answer 24

An energy level containing orbitals of the same number

Question 25

Shell

Answer 25

All orbitals of a principal energy level of an atom (1,2,3,4,5,6,7 etc)

Question 26

Subshell

Answer 26

All of the orbitals of an atom having the same principal energy level and the same letter designation (s p d f)

Question 27

Orbital

Answer 27

A region of space around nucleus that can hold a maximum of two electron (# of orbitals 1,3,5,7 for s,p,d,f respectively)

Question 28

S orbitals

Answer 28

Sphere shape with nucleus at center

Question 29

P orbital

Answer 29

Forms dumbbell shape

Question 30

Electron configuration

Answer 30

A description of the orbitals of an atom or ion occupied by electrons

Question 31

ELECTRON CONFIGURATION RULES

Answer 31

1. Orbitals fill in the order of increasing energy from lowest to highest 2. Each orbital can hold up to two electrons with spins paired 3. When there is a set of orbitals of equal energy, each orbital becomes half-filled before any of them becomes completely filled.

Question 32

Valence electron

Answer 32

Electron in the outermost occupied (valence) shell of an atom

Question 33

Valence shell

Answer 33

The outermost occupied shell of an atom

Question 34

Lewis dot structure

Answer 34

Symbol of the element surrounded by a number of dots equal to the number of electrons in the valence shell of an atom of that element

Question 35

PERIODIC PROPERTIES 1. Atomic Size

Answer 35

-Determined by the size of its outermost occupied orbital -increases from right to left, top to bottom; largest bottom left

Question 36

PERIODIC PROPERTIES 2. Ionization energy

Answer 36

-energy required to remove the most loosely held electron from an atom in the gaseous state. -always positive because energy must be supplied to overcome attractive force between electron and proton -increases left to right, bottom to top; largest top right -OPPOSITE TREND NI ATOMIC RADIUS

Question 37

Monoatomic atoms

Answer 37

Only noble gases (exist in nature) He Ne Ar Kr Xe Rn

Question 38

Molecules

Answer 38

-contain atoms of same element or atoms of two or more elements (Unlike compounds na dapat two or more elements)

Question 39

Allotropes

Answer 39

-one of two or more distinct forms of an element (i.e. Oxygen (O2) and Ozone (O3))

Question 40

Mass spectrometer

Answer 40

-most direct and most accurate method for determining atomic and molecular masses -gaseous sample is bombarded by a stream of high-energy electrons, producing positive ions; travels circular path with magnetic field -amount of current generated is directly proportional to number of ions; determines the relative abundance of isotopes