The Nature of Matter

Physical Sciences

BenchmarksA. Describe that matter is made of minute particles called atoms and

that atoms are comprised of even smaller components. Explain the structure and properties of atoms.

B. Explain how atoms react with each other to form substances and how molecules react with each other or other atoms to form even different substance.

C. Describe the identifiable physical properties of substances (e.g., color, hardness, conductivity, density, concentration, pH, and ductility). Explain how changes in these properties can occur without changing the chemical nature of the substance.

H. Trace the historical development of scientific theories and ideas, and describe emerging issues in the study of physical sciences.

Defining Matter

Matter - anything that has mass and takes up space.

Mass - the total amount of material in an object.

Tool to measure - triple beam balance Units - mg, g, kg, etc.

Defining Matter

Volume - the amount of space an object occupies.

The volume of liquids can be measured using a graduated cylinder or beaker.

Units are liters (L) or milliliter (mL).

The volume of irregular shaped objects are measured using water displacement with a graduated cylinder or beaker.

Units are liters (L) or milliliter (mL).

Defining Matter

The volume of a cube can be calculated by measuring the length of one side using a meterstick or ruler.

V = length X height X width

Ex.: If the length of one side of a cube is 2 cm, what is the volume?

V = 2 cm X 2 cm X 2 cm

V = 8 cm3

Defining MatterDensity - the amount of matter in a given space.

D = mass / volumeMass and volume both need to measured separately! The calculation

(ratio) of the two measurements equals the density.

Ex.: If the mass of a cube is 54 grams and the length of a side is 3 cm., what is the density of the cube?

First solve for volume: V = L X h X w V = 3cm X 3cm X 3cm

V = 27 cm3

Density = mass = 54 g = 2 g/cm3 volume 27 cm3

Chemistry

Elements - the building blocks of matter, a pure substance, made up of one type of atom.

Atom - the smallest particle of an element that has the properties of that element.

Substance - made up of one or more elements.

Compound - a combination of two or more atoms that maintains its own properties.

Molecule- smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.

Composition - what matter is made of and how it is organized

Chemistry

Properties - describes the characteristics, composition and behavior of matter, including the changes that matter undergoes.

1. Physical - characteristics that a sample of matter exhibits without any change in its identity. Solubility, melting point, boiling point, color, density, electrical conductivity, physical state.

2. Chemical - can be observed when there is a change in the composition of the substance. Iron at room temp with air = iron oxide (rust).

Chemical formula- shows the number and kind of elements in a substance

2NH3

Coefficient subscript

(number of molecules) (number of atoms)

Classifying Reactions

• Synthesis Reaction- Reaction in which two or more substances combine to form a compound. 2Na + Cl2 ------ 2NaCl

• Decomposition Reaction- Compound breaks into two or more substances. 2HgO ------ 2Hg + O2

• Single Replacement Reaction- One element replaces another element in a compound to form a new compound

Fe + CuSO4 ----- FeSO4 + Cu

• Double Replacement Reaction- Occurs when two compounds in a reaction exchange ions

AgNO3 + NaCl ----- AgCl + NaCO3

History

Greek philosophers (Democritus) created theories about indivisible matter: “Atomos” - meaning that which cannot be cut or divided.

Aristotle theorizes that everything is composed of Earth,

Water, Air, and Fire.

HistoryEarly 1800’s, John Dalton created the atomic theory: (4 parts)

1. All elements are made up of atoms. Atoms cannot be created, divided,or destroyed.

2. All atoms of the same element have the same size and mass.

3. Atoms of different elements have different sizes and masses.

4. During a chemical reaction, atoms are not destroyed, just rearranged.

Nuclear power disproves theorem number one. (Fission and Fusion)

Periodic Table

The Periodic Table

1869 Periodic table began to be organized by

Dmitri Mendeleev.

He organized elements due to physical and

chemical characteristics.

1. This was later called atomic number

a. number of protons

b. number of protons determines # of

electrons

2. Periodic repetition of properties

www.chemicalelements.com/

The Periodic Table

3. Elements in columns are called groups or families a. Total of 18 groups b. Groups have same characteristic and # of valence electrons

1. Ve-: electrons in outer shell c. as elements descend atoms grow larger

4. Elements in rows are called series or periods a. elements are arranged by inc. # of protons (atomic #) b. Total of 7 periods c. Descending periods increase electrons in shells. This is due to

increasing mass. d. As one goes across period atoms grow smaller.This is due to force of

charge pulling in electrons.

Atomic Mass and Numbers

Atomic Number – number of protons Number of protons determines the number of electrons in a neutral atom.

Atomic Mass – number of protons and neutrons Atomic mass minus atomic number equals the number of Neutrons.

The Periodic Table

3

Li

Lithium

6.941

Symbol

Name

Atomic Number

Atomic mass

LithiumProtons=3

Electrons=3Atomic

Mass=6.941Neutrons=4

Element Sizes

Electron Configurations

These are the most stable arrangement of electrons

There are 4 regions: s,p,d,f

s holds total of 2 electrons ___

p holds total of 6 electrons ___ ___ ___

d holds 10 electrons ___ ___ ___ ___ ___

f holds total of 14 electrons ___ ___ ___ ___ ___ ___ ___

Shells will fill up one at a time (like seats on a bus)

Electron Configurations

• Most stable arrangement of electrons

• 1s2

-The large number "1" refers to the principle quantum number "n" which stands for the energy level.  It tells us that the electrons of helium occupy the first energy level of the atom.

-The letter "s" stands for the angular momentum quantum number "l".  It tells us that the two electrons of the helium electron occupy an "s" or spherical orbital.

-The exponent "2" refers to the total number of electrons in that orbital or sub-shell.  In this case, we know that there are two electrons in the spherical orbital at the first energy level.

Oxygen: O 1s22s2 2p6

Bohr’ Models

• Model that illustrates subatomic particles for an element

Step 1: calculate total number

subatomic particles

Step 2: Create the nucleus by

drawing protons and

electrons

Step 3: Create electron shells

and attach the correct

amount of electrons

Step 4: Label all particles and

shells

Particle behavior

Hund’s Rule: electrons are negative, they have same charge and repel from each other, as far apart as possible.

Heisenberg Uncertainty Principle: 1920, impossible to measure accurately both the

position and energy of an electron at the same time.

Atomic Structure

Subatomic Particles: the particles below the surface of an atom. This includes protons, neutrons and electrons. An electrical force between nucleus and electrons holds the atom together.

atom: smallest particle of an element that has the chemical properties of that element.

1. a billion atoms laid end to end would make a line only 10cm long

2. atoms make up cells

Atomic Structure

A. electron: negatively charged particle orbits the nucleus1. electron is first to be discovered - 1891 2. lightest subatomic particle

B. proton: positively charged particle1. located in nucleus of atom - 1896

2. second lightest subatomic particleC. neutron: neutrally charged particle 1. located with proton in nucleus - 1932D. nucleus: holds protons and neutrons of atom

1. discovered in 19102. atoms are mostly empty space,distance between nucleus and electron is like a marble on the pitchers mound of a baseball field and the furthest seat in the stadium would be the electron.

Atomic Models

Electron Cloud Bohr’s Model