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? AAAAtomic number- number of protons in the nucleus of an atom. AAAAtomic Symbol MMMMass number- is equal to the number of protons and neutrons that make up its nucleus. EEEElement 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 2 0- 2 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