Science 10 - The Atom Mr. Jean February 3 rd, 2012

The plan: Video clip of the day Introduction to Chemistry What is matter?

Chemistry is the study of matter: What is matter? Matter is everything around us. Anything that takes up space or has a mass would be matter. Ex. Air, you, your desk.

Matter: Atomic particles Sub-atomic particles What is nothing? Why does stuff actually have mass?

Properties of matter: What properties can help you distinguish a metal from a non-metal? How can the periodic table help you predict ways that elements combine to form compounds? How can you use the periodic table to infer the names and formulas of compounds?

States of Matter Matter can be found in 3 states: 1. Solid 2. Liquid 3. Gas

Properties of matter: Physical properties: are observable and do not change the chemical composition of the matter. –ex.: colour, state of matter and smell.

Properties of matter: Chemical properties: are only observable through a chemical reaction, and do change the chemical composition of the matter. –Ex: burning something, reactivity with water..

Classify the following as a physical or chemical change: A) boiling water B) burning gas C) melting butter D) stretching an elastic band E) rusting a nail F) tearing a piece of paper G) rotting an apple H) water freezing

Mixtures and Pure Substances : Matter can be broken down into two categories: 1. Pure substance : substances containing only one type of atom or molecule. Ex: oxygen, water.. 2. Mixtures : most things around us are made of mixtures. Mixtures are a combination of or a mixture of pure substances. Ex: air, wood, dirt..

Types of Mixtures: Mixtures are broken up into 2 types: 1. Homogeneous mixtures : are uniformly mixed. Ex: air: is made up of oxygen, nitrogen, carbon dioxide, and water. 2. Heterogeneous mixtures : are not uniformly mixed. Ex: chocolate chip cookie.

Types of substances: Substances can be broken up into two groups: 1. Elements: are pure substance that cannot be broken down into smaller substances by ordinary means, such as a chemical reaction. Ex: all the elements on the periodic table like oxygen, carbon.. 2. Compounds: are pure substance made up of 2 or more elements that are chemically combined. Ex: water is made up of oxygen and hydrogen, and salt is made up of sodium and chlorine.

Periodic Table If you misplace your periodic table there is one in the science 10 text book. –Page 570 – 571

BBC – The Atom

The Atom The atom is the basic unit of matter. Everything is made up of matter, so everything is made up of atoms. Atoms are very small, and cannot even be seen by a regular microscope.

The Atomic Structure Atoms have no charge and are made up of several subatomic particles. They are: 1. Neutrons: are found in the center of the atom (nucleus). Have no charge or are neutral. 2. Protons: are also found in the center of the atom (nucleus). Have a positive charge. 3. Electrons: are found revolving around the nucleus of the atom in shells or electron clouds. Have a negative charge. The nucleus: is the center of the atom and is made up of protons and neutrons. (also has a positive charge)

The Atom Label the following atom. Include: Proton Neutron Electron Nucleus

What makes atoms different from one another? The number of protons, neutrons and electrons an atom has determines what kind of atom it is. Example: The oxygen atom has 8 electrons and protons therefore we know it is an oxygen atom. You can determine the number of electrons and protons an atom has by looking at its atomic number found on the periodic table.

Atomic Number The atomic number of an element is found on the periodic table. They are arranged in increasing order going from left to right. So Hydrogen has an atomic number of 1, Helium is 2 and so on. The atomic number tells us how many protons an atom has. This also tells us how many electrons an atom has, because the number of protons and electrons are balanced. So an atom has the same number of protons as electrons.

Calculating the number of electrons and protons an atom has: To calculate the number of protons and electrons an atom has we must look at the atomic number. Ex: Calculate the number of protons and electrons a Titanium atom would have.

Isotopes All atoms of the same type would have the same number of protons and electrons, but they don’t have to have the same number of neutrons. This can result in an isotope: atoms of the same type, but having different numbers of neutrons, changing the atomic mass. Question: Find out the three names of the three different isotopes that Hydrogen forms.

Atomic Mass The atomic mass of an atom also appears on the periodic table in weighted average form. (because of the isotopes). The atomic mass number of an atom is equal to the number of protons and neutrons it has. Formula: Atomic Mass # = # protons + # neutrons

Calculating the number of neutrons an atom has: To calculate the number of neutrons an atom has we must use the previous formula: Atomic Mass # = # protons + # neutrons Or # neutrons = Atomic Mass # - # protons Ex: Calculate the number of neutrons that the sodium atom has.