MATTER & THE ATOM Unit 2

THE ATOM

IN GENERAL…

Matter can be classified as either a PURE SUBSTANCE or a MIXTURE

Pure substances are further broken down into ELEMENTS and COMPOUNDS

The smallest unit of an element is an ATOM

ATOMIC STRUCTURE

Atom consists of three subatomic particles ProtonNeutron Electron

SUBATOMIC PARTICLES

Particle Symbol Charge Mass LocationProton p+ +1 1 NucleusNeutron n0 0 1 NucleusElectron e- -1 0 Electron

Cloud

VOCAB

Nucleons: particles in the nucleus (protons & neutrons)

Atomic Number (Z): number of protons in the nucleus, identifies element

Mass Number (A): sum of protons and neutrons in the atom (whole number)

Average Atomic Mass: average of all of the mass numbers of all the isotopes of an element (decimal on periodic table)

MORE DEFINITIONS

Isotopes: atoms of the same element with different # of neutrons (and therefore different masses) Protium (1H), deuterium (2H), tritium (3H)

Nuclides: specific isotope of an element EX Carbon-14 or Carbon-12

Ions: an atom with a charge because it gained or lost electrons lost electrons + charge (Cation)Gain electrons - charge (anion)

ISOTOPE NOTATION

Atomic # _______

Mass # ________

# Protons _______

# Neutrons ______

# Electrons ______

3157

+N

PRACTICE – ISOTOPE NOTATION

Calcium – 41

Sodium – 23

Bromine-81

HYPHEN NOTATION

Nitrogen – 15

Nitrogen – 14

What is different?

What is the same?

HELPFUL HINTS

Neutral atoms: # protons = # electrons

# neutrons = mass # - atomic #

Ions: # electrons = atomic # - charge

PRACTICE – SOLVING FOR SUBATOMIC PARTICLESElement Atomic # Mass # Average

Atomic Mass

Protons Neutrons Electrons Isotope Notation

Ca

Bromine-81

Na+1

W

P-3

WARM UP – 2/1 COMPLETE THE CHART BELOWElement/ion Atomic

#Mass # Avg.

Atomic Mass

P+ n0 e- Isotope notation

Chlorine-36

6 8

20 18

Nickel-60

AVERAGE ATOMIC MASS

Weighted Average of all the mass numbers of all the isotopes of that element

EX: Calculate the average atomic mass of boron if a sample contains19.78 % Boron-10 (10.013 AMU)80.22% Boron-11 (11.009 AMU)

MORE EXAMPLES

What is the average atomic mass of an element with the following isotopes?

Magnesium-24 78.70%

Magnesium-25 10.13%

Magnesium-26 11.17%

MORE EXAMPLES

Calculate the average atomic mass of isotope X

If an isotope of Xenon has a mass of 133 AMU is it the most abundant isotope that exists for this element? Why or why not?

Mass Number Exact Weight Percent Abundance

14 14.003074 99.63

15 15.000108 0.37

WARM UP – 2/4

Determine the number of each subatomic particle in the following isotopes

50120𝑆𝑆𝑆𝑆 9

17𝐹𝐹 38𝐿𝐿𝐿𝐿

What is the average atomic mass of titanium?

MATTER & ITS PROPERTIES

VOCAB

Mass: the amount of matter (g or kg)

Matter: anything that has mass and takes up space (not energy!)

Atom: smallest unit of an element that is still that element

Element: Pure substance made of 1 kind of atom (on Periodic Table) EX: sodium, uranium, gold, oxygen

Compound: Pure Substance made of 2 or more elements chemically combined EX: salt, sugar, vinegar, water

PROPERTIES OF MATTER

Properties of matter are unique and can be used to distinguish between and identify different substances

Physical Properties: can be observed/measured without changing the substance Extensive Property: depends on the amount of matter present (external)Volume, mass, amount of energy Intensive Property: does NOT depend on the amount of matter (internal)Melting Point, Boiling Point, Density, Conductivity (electrical and heat)

EXTENSIVE VS INTENSIVE PRACTICE

Determine the extensive and intensive properties below

A student is conducting an experiment to see how long it takes to boil water. She places 5 mL of water on a hot plate and 3 L of water on a hot plate at the same temperature. When she reads the thermometer at boiling she sees that both have a temperature of 100oC.

PHYSICAL CHANGES

Physical Change: change in a substance that does not change the identity EX: Grinding, cutting, melting, boiling, tearing

Change of state: physical change that alters the state of matter EX: Boiling, freezing, condensing

STATES OF MATTER

Solid: definite volume, definite shape, particles vibrate around a fixed position

Liquid: definite volume, indefinite shape, particles flow around one another. Particles assume shape of container

Gas: indefinite volume, indefinite shape, particles move rapidly and are far apart. Fill containers completely

CHEMICAL PROPERTIES AND CHANGES

Chemical Properties: Relates to a substance’s ability to change into something else Flammability, able to rust, able to decompose, reactivity

Chemical Change: change in which a substance becomes something else Rusting, burning, rotting

CHEMICAL CHANGES ARE CHEMICAL REACTIONS (RXN)

WRITING CHEMICAL CHANGES

Reactants: substances that react in a chemical change (what you start with)

Products substances that are formed by the chemical change (What you end with)

H2 + O2 H2O

Reactants yield Products

INDICATORS OF CHEMICAL CHANGE

Color change

Gas released

Heat released or absorbed

Formation of a precipitate (solid that forms when to solutions react)

***Only way to be 100% sure is to test for the new substance

PRACTICE – PHYSICAL OR CHEMICAL CHANGEBreaking a pencil

Wood burning

Silver tarnishing

Ice melting

Hard boiling an egg

Grinding coffee beans

Burning gasoline

WARM UP – 2/6

Classify the following as chemical or physical changes

-Burning a pile of leaves

-Crushing an ice cube

-Cooking a steak

-Melting a bar of gold

CLASSIFICATION OF MATTER

MORE VOCAB

Mixtures: a blend of two or more substances that are NOT chemically combined. Each substance retains its own identity and properties. Mixtures vary in composition

Homogeneous: uniform composition throughout (SAME) Salt water, kool-aid, sweet tea

Heterogeneous: composition varies throughout (DIFFERENT) Soup, yogurt with fruit in it, bag of M&Ms

PRACTICE – HOMO OR HETERO

Stainless Steel

Granite

Air

Blood

Hand lotion

Oil and Water

Bird Seed

Chunky peanut butter

Dirt

MATTER FLOW CHART

PURE SUBSTANCES VS. MIXTURES

Pure substances have the same properties and composition everywhere Boiling point of water is the same here, in NYC, Paris, etc. Water is ALWAYS H2O, Glucose is ALWAYS C6H12O6

FANCY MIXTURES

Solution: homogeneous mixture of any phase! EX Soda, air, coffee

Suspension: heterogeneous mixture whose particles settle out over time and can be separate by filtration EX Muddy water

Colloid: special suspension whose particles don’t settle out and cannot be filtered. They scatter light (Tyndall effect) EX: Fog, milk, mayonnaise