ATOMS Standard C-2 Students will demonstrate an understanding of atomic structure and nuclear processes.

What is MATTER? Matter is anything with a mass and volume Matter is made of things called ATOMS.

Matter Can Be a PURE substance or a MIXTURE Elements Cannot be decomposed into simpler substances Gold Compounds Can be decomposed into simpler substances by chemical change Carbon dioxide, CO2

Matter Can Be a PURE substance or a MIXTURE Elements: Compounds: Individual elements represent individual atoms Compounds are molecules Molecules are made up of two or more atoms

ATOMS An atom is the smallest particle of an element that retains its identity in a chemical reaction Made up of 3 subatomic particles Protons Neutrons Electrons

Protons p+ Positively charged Relative charge 1+ Found in nucleus

Neutrons n0 No charge Approximately the same mass as proton Found inside the nucleus

Electrons e- Negatively charged Relative charge 1- Found in electron cloud Found in different energy levels n= 1, 2, 3, …

Reading a Periodic Table Atomic # Element Atomic Mass

Atomic Mass - Atomic Number Is the number of PROTONS This is also the number of ELECTRONS Is the total number of PROTONS and NEUTRONS # of Neutrons Atomic Mass - Atomic Number

APE Atomic Number Equals Protons Electrons

MAN Mass Minus Atomic Number Equals Neutrons

Practice How many protons does carbon have? How many neutrons does carbon have? 12 – 6 = 6 neutrons How many electrons does carbon have? 6 electrons

Practice How many protons does chlorine have? How many electrons does chlorine have? 17 electrons How many neutrons does chlorine have? 35 – 17 = 18 neutrons

Isotopes Is an element that has a different number of neutrons and different atomic mass.

Hydrogen Isotopes The most common type of hydrogen is called protium Nucleus only consists of one proton and zero neutrons.

Bohr Model Bohr model places electrons in energy levels Electrons orbit around nucleus like the planets around the sun n=4 n=3 n=2 n=1 nucleus

# of e- = 2(n2) n = energy level nucleus

# of e- = 2(n2) n = energy level 2(12) = 2 electrons in the 1st energy level n = 3 2(32) = 18 electrons in the 3rd energy level

Carbon Bohr Model Carbon has 6 electrons Nucleus 6 electrons -2

Chlorine 17 electrons -2 =15 electrons -8 =7 electrons Nucleus