Intro to AtomsAtoms: the basic particle in which all elements are

madeNucleus: The central core of an atom containing

protons and neutronsIn the nucleus are:

• Proton: small, positively charged particle in the nucleus of an atom ( + symbol)

• Neutron: Neutral charged particle in the nucleus of an atom

Outside the Nucleus:• Electron: tiny, negatively charged particle that

moves around the nucleus of an atom

Laws of Science

Law of Conservation of Matter• Matter cannot be created or destroyed

Law of Conservation of MassEstablished by French Chemist Antoine Lavoisier• In a chemical reaction, the mass of the

products equals the mass of the reactants. THIS IS EXTREMELY IMPORTANT WHEN

BALANCING EQUATIONS

What’s the MATTER?Matter: anything that has mass and takes up

space.Mass: measurement of how much matter is in

an objectElement: a substance that cannot be broken

down into any other substances by chemical or physical means

Compound: a substance of 2 or more elementsMixture: 2 or more substances that are mixed

together, but NOT chemically combined

Atomic ModelsEarly Models/Theories of the Atom:

Dalton’s Atomic Model:- All matter is composed of atoms- Atoms cannot be made or destroyed- All atoms of the same element are identical- Different elements have different types of atoms

- Atoms of 2 or more elements can join together to form a compound

Modern Atomic Model – NOT ON YOUR PAPER!

• Electrons form a negatively charged cloud around the nucleus

• Cannot determine the location of an electron at any given time

Atomic Models continued…

JJ Thomson’s Model:• Atom is positively charged• Discovered Electrons

Rutherford’s Model:• Protons and the nucleus• Electrons orbit around the positively charged nucleus

Chadwick’s Model:• Discovered neutrons

Bohr’s Model:• Electrons move in specific layers (shells)• Electrons move when atoms absorb or give off energy, moving

from one shell to another

Atoms and ElementsAtomic number • number of protons in an element • Number of electrons the element hasAtomic mass: mass of one atom of the elementHow to calculate neutrons: atomic mass # - atomic

numberValence electrons: electrons that can be transferred

from one atom to another or may be shared between atoms

Chemical symbol: symbol for element (H – Hydrogen) (C – Carbon)

Periodic TableDmitri Mendeleev

• Created first Periodic Table• Arranged elements in order of increasing

atomic mass• Placed similar elements in the same group

according to their reactionsPeriods: a horizontal row in the P.T. Groups: vertical columns in the P.T. – also known

as families due to similar characteristics

Groupings

• Metals (Alkali , Alkali Earth)• Nonmetals• Nobel Gases• Transition Elements• Halogens• Common Elements

Valence Shells

Group 1 = 1 valence electronGroup 2 = 2 valence electronsGroup 13 = 3 valence electronsGroup 14 = 4 valence electronsGroup 15 = 5 valence electronsGroup 16 = 6 valence electronsGroup 17 = 7 valence electronsGroup 18 = 8 valence electrons (full shell)

Properties of Metals

• Classified by its physical properties such as shininess, malleability, ductility, and conductivity.

Malleable: can be hammered flat or into other shapes

Ductile: can be pulled out into a long wireConductivity: ability to transfer heat from one

object to another

Metals continued…

Chemical properties: ability of a pure substance to change into another substance.

Reactivity: The speed in which an element combines or reacts with other elements

Corrosion: the wearing away of metal due to a chemical reaction

Metals can be considered an alloy which is a mixture of a metal with one other element (usually found together in nature)

Physical and Chemical Properties

Physical• Def: a change that does not

result in the formation of any new substances

• Examples: Dissolving sugar in waterMelting ice cubesBoiling waterCrumbling Paper

Chemical• Def: a change that

produces one or more new substances

• A chemical reaction will take place

• Burning paper• Corrosion • Rusting• Milk or eggs going BAD

Nonmetals

• Lack the properties of metals• Poor conductors of electricity and heat• Reactive with other elements• Dull and brittle (break easily)• Good insulators

Metalloids & Noble Gases

Metalloids• Metalloids has

characteristics of both metals and nonmetals

• Semiconductors: substances that can conduct electricity under some conditions

Noble Gases• Unreactive elements• Exist in Earth’s atmosphere