2The Building Blocks of Matter Anything that:has masstakes up space
3The Building Blocks of Matter AtomsTiny particles that make up matter.Properties of an object are determined by:the atoms that make up the objectthe way in which those atoms join together
4The Building Blocks of Matter ElementsSubstances that are made up of only one type of atom.Cannot be broke down into simpler substances by normal chemical or physical means.There are about 90 naturally occurring elements on Earth.
5Modeling the Atom Atoms are made of: Protons Neutrons Electrons Have a positive electrical chargeNeutronsHave no electrical chargeElectronsHave a negative electrical charge
6Modeling the Atom Model by Niels Bohr - 1913 Nucleus Located at the center of the atomContains both protons and neutronsElectrons travel in orbit-like paths around the nucleus.Electrons in orbits farther from the nucleus have more energy than electrons in orbits closer to the nucleus.
7Modeling the Atom Current Model Electrons are grouped into energy levels.Each energy level holds a specific number of electrons.Electrons are located anywhere within an electron cloud that surrounds the nucleus.Usually located close to the nucleus.
8Counting Atomic Particles Atomic NumberEqual to the number of protons in the element.Moving left to right through the periodic table, the atomic number of each element increases by one.
9Counting Atomic Particles Mass NumberEqual to the number of protons plus the number of neutrons.So, mass number – atomic number = number of neutrons
10Counting Atomic Particles How many electrons?In a neutral atom, the number of protons equals the number of electrons.
11Counting Atomic Particles IonsAtoms of an element that have a charge.Lose electrons (positive charge)Gain electrons (negative charge).
12Counting Atomic Particles IsotopesAtoms of the same element that have different numbers of neutrons.
13Review Number of Protons = Number of Neutrons = Number of Electrons = Atomic numberNumber of Neutrons =Mass number – number of protonsNumber of Electrons =Number of protons (in a neutral atom)