What is an atom?  They are the building blocks of all matter.  Everything is made of atoms.  Example: Legos

What makes up an atom?  Protons- particles that have a positive charge.  Neutrons- particles that have a neutral charge.  Protons and Neutrons form the Nucleus of the atom.  Electrons- particles that have a negative charge. Electrons Protons and Neutrons Nucleus

What is on a periodic table? AAAAtomic number- number of protons in the nucleus of an atom. AAAAtomic Symbol MMMMass number- is equal to the number of protons and neutrons that make up its nucleus. EEEElement Name O 8 16 Oxygen Link

What is an isotope?  Atoms of the same element with different numbers of neutrons in the nucleus.  Having a different number of neutrons will not change the element, but it will change the mass. Carbon 12 Carbon- 6 protons + 6 Neutrons = Mass Number of 12 Carbon 14 Carbon- 6 protons + 8 Neutrons = Mass Number of 14 Isotopes

What are isotopes used for?  Medical purposes  Determining the age of ancient objects  Example: Carbon-14 is used for carbon or radioactive dating of ancient objects

How do atoms combine?  Sharing electrons in there outermost portion of their electron cloud. This is called a covalent bond  Example- H 2 0 (water)  By losing or gaining electrons. This is called an Ionic bond  Example NaCl (salt)

Sharing Electrons  H atoms of hydrogen can share electrons with 1 atom of oxygen to form 1 molecule of water  Hydrogen has 1 electron in its outer shell to be shared. Electrons being shared

Gaining and Losing Electrons  When an atom loses electrons, it has more protons that electrons so the atom is positively charged.  When an atom gains electrons, it has more electrons than protons so the atom is negatively charged.

IONS  Sodium (Na) atom loses an electron and becomes a positively charged ION.  Then it comes close to a negatively charged Chlorine (Cl) ION to form NaCl.  Na + Cl = NaCl

What is an Ion?  Electrically Charged Atoms  They are attracted to each other when they have opposite charges.  The atom has either gained or lost an electron making it a charged atom.

What is the difference between a compound and a mixture?  A new substance that forms when elements combine.  Cannot be separated back into the individual elements by physical means.  Example: Hydrogen and Oxygen, which are gases, combine to form water. The gases cannot be separated back.  Do not change into something new when mixed together.  Can be separated back into their individual substances.  Example: In trail mix, the raisins and peanuts don’t change into a new substance. It’s easy to separate them back. CompoundMixture