Presentation on theme: "An atom –smallest basic unit of matter"— Presentation transcript:
1KEY CONCEPT All living things are based on atoms and their interactions.
2An atom –smallest basic unit of matter Contains:a. nucleus has protons and neutrons.b. electrons are in energy levels – regions around the nucleus.Oxygen atom (O)Nucleus: 8 protons (+) 8 neutronsoutermost energy level: 6 electrons (-)inner energy level: 2 electrons (-)
6ElementsMatter that has atoms that are all alike are elements.Elements cannot be broken down into smaller substances.Elements are listed on the Periodic Table.More than 90% of the human body is made of only carbon, hydrogen, oxygen, and nitrogen.
7Most abundant elements The most common elements found in living things are Carbon, Hydrogen, Nitrogen, and Oxygen.Oxygen, at 65%, is the element that makes up most mass in the human body.Carbon follows with 18.5%, then hydrogen with 9.5%, and then nitrogen with 3.3%.
8Living things consist of atoms of different elements. An atom is the smallest basic unit of matter.An element is one type of atom.Hydrogen atom (H)HOOxygen atom (O)
9O A compound is made of atoms of different elements bonded together. water (H2O)OH_+
10A compound is made of atoms of different elements bonded together. water (H2O)carbon dioxide (CO2)Glucose
11An ion forms when an atom gains or loses one or more electrons. positive ions -formed when atoms lose electronsnegative ions -formed when atoms gain electronsIonic bonds –chemical force due to electircal attraction between oppositely charged ions.Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na+)Chloride ion (CI-)Na loses an electron to CIionic bondgained electron
13Molecules- atoms bonded together by covalent bonds Covalent bonds form when atoms SHARE electrons in their outer energy level. This allows both atoms to become full and stable.covalent bondsOxygen atom (O)Carbon atom (C)Carbon dioxide (CO2 )
14Covalent bondsMost organic (coming from living things) compounds have covalent bonds.This includes sugars, fats, proteins, and water.
17Compounds you need to know: H2O = waterCO2 = carbon dioxideC6H12O6 = sugar (usually glucose)NaCl = table saltNH3 = ammonia
18IsotopesAtoms with the same number of protons and electrons but different numbers of neutrons are called isotopes.Isotopes have the same element, but may have different properties because of their different masses that may change its stability.Isotopes are named by adding the number of protons and neutrons.Some isotopes are useful in telling the age of fossils.