Atoms Review

Size of Atoms Remember our zoom in on Atoms? How small are atoms? What are Atoms?

Elements What is the definition of an element? What are some examples of elements?

Scientific Shorthand Element Symbol Aluminun Al Iron Fe Gold Au Mercury Hg Oxygen O Chlorine Cl

Why the weird Short hand? Silver is argentum in Latin - hence Ag Gold is aurum in Latin - hence Au Potassium is named after the Latin word for “alkali” kalium - hence K. Potassium is one of the alkali metals Mercury’s former name was “hydrargyrum” from the Greek words for water and silver – Hg Sodium from the Latin natrium - hence Na Iron from the Latin ferrum - hence Fe

Why use Chemical Symbols? ● Easier to write H v. Hydrogen, or H2O for dihydrogen oxide ● Used worldwide Scientists regardless of language use chemical symbols

Parts of Atoms Where is the nucleus and Electron Cloud? Which particles are protons? Electrons? Neutrons?

What Makes up an Atom? Nucleus - small positively charged center of an atom. Protons - particles with a charge of 1+ Neutrons - particles with no electrical charge Electrons - particles with a charge of 1- Atoms of different elements differ in the number of protons they contain

Reading the Periodic Table If the atomic number is 7, how protons are there? How many electrons? If the atomic mass is 14.95, how many neutrons are there?

Using the Period table Practice Turn to the periodic table in your planner (R-13), and find out how many protons, neutrons, and elections are in each of these elements. Na S Ar Ti Be In N Br

What is the definition of a Molecule? What are some examples? molecules What is the definition of a Molecule? What are some examples?

All Compounds are molecules!! What is the definition of a compound? Examples?

Why Do we have different States of Matter? What are the states of matter like?

STATES OF MATTER LIQUID PLASMA SOLID GAS Tightly packed, in a regular pattern Vibrate, but do not move from place to place Close together with no regular arrangement. Vibrate, move about, and slide past each other Well separated with no regular arrangement. Vibrate and move freely at high speeds Has no definite volume or shape and is composed of electrical charged particles

History of atoms What are some discoveries scientists have made about atoms since Democritus?

Quantum Mechanical Model

Composition of Matter Notes

1 Pure Substances Materials are made of a pure substance or a mixture of substances. A pure substance, or simply a substance, is a type of matter with a fixed composition. A substance can be either an element or a compound.

Composition of Matter 1 Elements All substances are built from atoms. If all the atoms in a substance have the same identity, that substance is an element. The graphite in your pencil point and the copper coating of most pennies are examples of elements.

Composition of Matter 1 Compounds Can you imagine yourself putting something made from a slivery metal and a greenish-yellow, poisonous gas on your food?

Composition of Matter 1 Compounds Table salt is a chemical compound that fits this description. Even though it looks like white crystals and adds flavor to food, its components—sodium and chlorine—are neither white nor salty.

Composition of Matter 1 Mixtures A mixture, such as the pizza or soft drink shown, is a material made up of two or more substances that can be easily separated by physical means.

Heterogeneous Mixtures Composition of Matter 1 Heterogeneous Mixtures Unlike compounds, mixtures do not always contain the same proportions of the substances that make them up. A mixture in which different materials can be distinguished easily is called a heterogeneous mixture.

Heterogeneous Mixtures Composition of Matter 1 Heterogeneous Mixtures Most of the substances you come in contact with every day are heterogeneous mixtures. Some components are easy to see, like the ingredients in pizza, but others are not. For example, the cheese in pizza is also a mixture, but you cannot see the individual components.

Composition of Matter 1 Homogeneous Mixtures Soft drinks contain water, sugar, flavoring, coloring, and carbon dioxide gas. Soft drinks in sealed bottles are examples of homogeneous mixtures.

Composition of Matter 1 Homogeneous Mixtures Another name for homogeneous mixtures like a cold soft drink is solution. A solution is a homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle to the bottom of their container. Solutions remain constantly and uniformly mixed

Heterogeneous Mixture Breakdown of Matter Matter Pure Substances Mixtures Element Compound Heterogeneous Mixture Homogeneous Mixture

Quick Practice Substance Mixture or Pure Homogeneous or Heterogeneous Soda Steel Oxygen Iron filings smoke Limestone (CaCO3)

Key Concepts Every sample of a given substance has the same properties because a substance has a fixed, uniform composition An element has a fixed composition because it contains only one type of atom A compound always contains two or more elements joined in a fixed proportion The properties of a mixture can vary because the composition of a mixture is not fixed