Chapter 3: The Building Blocks of Matter

Belived that atoms were invisible and they moves and combined in different ways. Purely speculative

Democritus

Believed that all matter was composed of the four basic elements, earth, wind, fire, and water. More influencial then Democritis. The theory survived until science and expiriments came around.

Aristotle

Matter is not created nor destroyed in any chemical or physical change

Law of Conservation of Mass

A chemical compound contains the same elements in the same proportions of mass.

Law of Definite Proportions

Concluded that matter could be explained in terms of atoms

Dalton's thoughts on matter

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

Dalton's Atomic Theory

measured the charge-to-mass ratio of an electron. Discovered that atoms are divisible! and discovered the electron

Thomson's Cathode Ray Experiment

Positive

Protons charge

Negative

Electrons charge

Atom

Thomson's Plum Pudding Model of the _______

Discovered that all positives are concentrated into the center (nucleus).

Rutherford's Gold Foil Experiment discoveries

Alpha-particles were directed at a thin sheet of gold foil; most passed through the foil, but a few were deflected; this led to the discovery of the atomic nucleus.

Rutherford's Gold Foil Experiment

Sprayed oil droplets between electrically charged plates

Milikan's Oil Drop Experiment

Discovered the charge of electron, and ues dimensional analysis and calculated the mass of electron

Milikans Oild Drop expiriment discoveries

the number of protons in the nucleus of an atom

Atomic number

On top

Where is the atomic number located on the Periodic table?

The basic unit of a chemical element. The smallest unit

Atom

Atomic Number

How to determine an atoms identity?

neutral. The number of protons minus the number or neutrons.

Charge of an atom

1 amu

Mass of proton

1 amu

Mass of neutron

0 amu

Mass of electron

Strong neuclear force

How is the neuclus held together?

Holds the protons and neutrons together in the neucleus

Role of Strong Nuclear Force

Contain the same number of protons

Isotope Similarities

Contain different numbers of neutrons

isotope differences

Same as atomic number

Determine the number of protons in an isotope

Protons minus the charge

Determine the number of electrons in an isotope

Protons minus electrons

Determine the number of neutrons in an isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Isotope

An atom or group of atoms that has a positive or negative charge.

Ion

A solid sphere of matter that was uniform throughout

Daltons model

Plum Pudding. Electrons in a sea of positive goo.

Thompsons model

Concluded atoms consist mostly of empty space where electrons move and also have a positively charged molecule in the center

Rutherfords model

The atomic weight of any atom can be found by multiplying the abundance of an isotope of an element by the atomic mass of the element and then adding the results together.

Calculating atomic weight of an element given the weight of each isotope and relative abundance

(g) (1 mole/# g)

Mass to moles

(moles) (6.022 x 10^23/ 1 mole)

Moles to particles

atoms, molecules, formula units

Particles

6.022 x 10^23

Avagadro's number

Theory is testable

Idea vs. Theory

1) elements are composed of atoms.

Daltons Theory Principle 1

2) Atoms of same element are identical, but differ from other elements.

Daltons Theory Principle 2

atoms only change when mixed with other elements

Daltons theory principle 4

3) Elements can mix together

Daltons theory Principle 3

When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers

Law of Multiple Proportions (Dalton)

Negative electrode

Cathode

positively charged particle, found in the neuclues

Proton

A small particle in the nucleus of the atom, with no electrical charge

Neutron

electron and proton

The subtomic particles that are least massive and most massive, respectivly are the...

Neutral charged

Atom

Balance of the proton and electron

Why is an atom neutral?

Chlorine- 37 ion

Given the # protons is 17 and the # neutrons is 20, with a 1- charge. What is the name of the ion?

17

Given the # protons is 17 and the # neutrons is 20, with a 1- charge. What is the atomic #

37

Given the # protons is 17 and the # neutrons is 20, with a 1- charge. What is the mass #

37

Given the # protons is 17 and the # neutrons is 20, with a 1- charge. What is the # of particles in the neuclues?

21

Given the # protons is 17 and the # neutrons is 20, with a 1- charge. What is the # of electrons?

Mass number

When writing the symbol which number goes at the top left?

Atomic number

When writing the symbol which number goes at the bottom left?

Charge

When writing the symbol which number goes at the top right?

False, it depends on the number of electrons

T or F: In a neutral atom, the number of protons is equal to the number of neutrons.

True

T or F: When an atom loses or gains electrons, it is called an ion

False, it depends on your neutron.

T or F
atoms with the same number of protons and different numbers of electrons are called isotopes.

atomic mass unit, 1/12 of the mass of a carbon-12 atom

AMU

the weighted average of the masses of the isotopes of an element

Atomic mass

the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12

Mole

the mass of one mole of a pure substance

Molar mass

Mass number on periodic table

g=