Unit 2 Chapter 3 Matter and Atomic Structure

VOCAB Matter Periodic table Atom Proton Neutron Element Solid Liquid Gas Sublimation Evaporation Ionic Bond Covalent bond Acid Base Condensation Solution Homogenous mixture Heterogenous mixture WRITE ALL VOCAB WORDS DOWN BEFORE YOU START YOUR DEFINITIONS!! VOCAB DUE: MONDAY 9/14

Section 1 Objectives: –Describe the particles within atoms and the structure of atoms. –Relate the energy levels of atoms to the chemical properties of elements. –Define the concept of isotopes.

What is matter? Matter is anything that has volume and mass. On earth these are found as solids, liquids and gas.

Everything on Earth and beyond is made of substances called elements. What is an ELEMENT? An element is a substance that cannot be broken down into simpler substances by physical or chemical means.

Example If I were to melt gold necklace in a pot it would no longer be solid but it would still be gold. No matter what form it’s still gold!

Elements There are 92 natural elements Others have been artificially created All elements are identified by a chemical symbol that is 1-3 letters long. (Ex: H stands for Hydrogen) They are all grouped together in the periodic table! Elements that were present in ancient times have different symbols, that represent their latin origin. Like Gold with the symbol Au for the latin word Aurum.

Each element has distinct characteristics. Elements are made up of atoms.

What is an Atoms? Atoms are the smallest particle of an element that has all the characteristics of that element. Consists of protons, electrons & neutrons and a nucleus in the center.

Nucleus- the center of an atom. Made up of protons & neutrons. Proton- a tiny particle that has a mass & a positive electrical charge. Neutron- has the same mass as the proton, but electrically neutral.

All nuclei are positive. WHY? Because they are made up of positive protons and neutral neutrons.

All atoms contain different numbers of protons and neutrons. –Hydrogen – smallest atom Hydrogen only has 1 proton in the nucleus –Uranium- heaviest Uranium 238 has 92 protons and 146 neutrons

Number of protons in an atoms nucleus is the atomic number –Ex. Carbon has 6 protons so therefore it’s atomic number is 6 Number of protons + neutrons = atomic mass or mass number –Ex. Carbon has 6 protons and 6 neutrons for a atomic mass of 12

~ELECTRONS~ Electrons

Although they are really tiny they have a electrical charge that is NEGATIVE! That charge is the exact same magnitude as the proton. ATOMS HAVE THE SAME NUMBER OF PROTONS AND ELECTRONS!! So since 1 electron has the same charge as 1 proton and there are the same amount of each. What would be the over all charge of an atom??

NONE! ZIP! ZERO! NADA!!! It has NO charge!!!

What are ENERGY LEVELS? Energy levels represent the area in an atom where an electron is most likely to be found.

This is a silver atom These are different energy levels

These energy levels are kind of like bedrooms in a house. Different houses have different number of bedrooms and can sleep different number of people. Each energy level can only hold so many electrons. The larger the energy level the more electrons it can hold.

The smallest energy level can only hold 2 electrons. The second energy level can hold 8 The 3 rd can hold 18 and the 4 th can hold 32! Some atoms can have up to 7 energy levels!!! Each level is larger than the last and has more room for more electrons, just like bigger houses have more room for bigger families!

Electrons always want to have their energy levels full so they will occupy the lowest available level. The electrons in the outermost energy level determine the chemical behavior of the elements. The outermost electrons are called VALENCE ELECTRONS! Elements with the same number of valence electrons have similar properties.

Elements with 1 valence electron are very reactive like Potassium and Sodium, they combine well with other elements. Because they want to fill their energy levels! If an elements energy levels are full it is inert, which means it doesn’t react easily with other elements. Helium, Neon and Argon are inert Because their energy levels are all full! You can find out much of this information just by looking at your periodic table!!

What are ISOTOPES? Atoms of the same element with different mass numbers. We know that all atoms have the same number of protons but they don’t always have the same number of neutrons!

The average of the mass numbers of the isotopes of an element. What is ATOMIC MASS?

The nucleus of some isotopes is unstable and release RADIOACTIVITY!!!! Radioactivity is the spontaneous process through which unstable nuclei emit radiation.

FUN FACTS!!! During radioactive decay, a nucleus can lose protons and neutrons, change from proton to neutron or vice versa, this changes the identity of the element. EX: Uranium 236 decays to Lead 206 and Uranium present in rock is eventually replaced with lead. By measuring the amount of uranium and lead in rocks we can determine their age!!!