The Atom Chapter 11 Section 2

Atoms An atom is so small… atoms – the smallest particles into which an element can be divided and will remain the same substance make up elements often called the building blocks of matter An atom is so small… A penny contains 2 x 1022 atoms Or 20,000,000,000,000,000,000,000 atoms! It would take a stack of 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil!

Parts of an Atom BrainPOP Atom Even though an atom is tiny, it consists of even smaller parts/particles: Nucleus Electron Cloud nucleus – small, dense, positively charged center of the atom contains most of the atom’s mass Particles inside the Nucleus: Proton Neutron electron cloud – region around the nucleus of an atom where electrons are found contains most of the atom’s mass Particles outside the Nucleus: Electron

Inside the Nucleus: Protons protons - positively charged particles of the nucleus All are identical Each proton has an amu (atomic mass unit) of 1 Write/Say as: 1 amu

Inside the Nucleus: Neutrons neutrons - particles of the nucleus that have no charge All neutrons are identical While neutrons are a bit larger than protons, they are not enough bigger to have a larger amu. Neutron = 1amu

Outside the Nucleus: Electrons electrons - negatively charged particles in atoms around the nucleus within electron clouds 1st Level: 2 Electrons 2nd Level: 8 Electrons 3rd Level: 18 Electrons charges of protons and electrons are opposite but equal in size mass 1 proton ≈ 1800 electrons! Electrons are so small the mass is usually considered to be zero! 2 8 18

Building Atoms Let’s build the simplest atom…the hydrogen (H) atom Proton Electron

Can we build bigger atoms? Sure! Try this on your own paper… A carbon atom has 6 protons, 6 neutrons, and 6 electrons or An oxygen atom that has 8 protons, 9 neutrons, and 8 electrons

IN Activity: Summarize 3 – 2 – 1 Review! On your output page: 3 Particles in an Atom 2 Main Parts of an Atom 1 The Building Blocks of Matter