2.1 – Atoms, Ions, and Molecules
Do Now: In terms of chemistry, what do a frog, a skyscraper, and your body all have in common?
Atoms Atom- smallest basic unit of matter It would take more than 1 trillion years to count the atoms in a single grain of sand H O Hydrogen atom (H) Oxygen atom (O)
Subatomic Particles Atoms are made up of 3 smaller parts: 1. Protons (+) – Found in nucleus 2. Neutrons (0) – Found in nucleus 3. Electrons (-) – Energy levels outside of nucleus Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)
Elements Element- one particular type of atom, cannot be broken down If all elements are made up of atoms… what distinguishes between elements?
Reading the periodic table:
Elements in living things “CHNOPS” Carbon, Hydrogen, Oxyen, and Nitrogen make up about 95% of our body Sulfur is needed for proteins Phosphorous is needed for DNA You must memorize these!!!!!
Compound Compound- a substance made of atoms of different elements bonded together in a certain ratio A compound has different properties than the elements that it is made of What type of chemical compounds have we talked about so far this year? O HH _ ++
Carbon Dioxide
Example: Hydrogen and Oxygen are both found as gases naturally on earth BUT… when combined they can form water A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.
Bohr Models Niels Bohr, 1913 Showed a positively charged nucleus surrounded by negatively charged electrons Useful for showing bonds in chemical compounds See handout for rules!
Practice: In your notes, draw the correct Bohr diagram for: Carbon (C) Atomic number = 6 Mass = 12 Sodium (Na) Atomic number = 11 Mass = 22
Quick review: How are elements different from compounds? Give at least 2 reasons:
Ions form when atoms gain or lose electrons. An ion is an atom that has gained or lost one or more electrons. positive ions negative ions Ionic bonds form between oppositely charged ions. They are held together by electrical force! Easily dissolve in water! Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron
Ionic Bond Example:
How do we know if an atom wants to gain or lose electrons? The atom wants a full energy level by moving the LEAST amount of electrons So… If it has 3 or less electrons it will give electrons away and become POSITIVELY charged If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged
Atoms share pairs of electrons in covalent bonds. A covalent bond forms when atoms share a pair of electrons. Usually very strong! covalent bonds Oxygen atom (O)Carbon atom (C)Oxygen atom (O) Carbon dioxide (CO 2 ) –multiple covalent bonds –diatomic molecules –Ex: O 2
Molecules Molecule- two or more atoms held together by covalent bonds
One last type of bonding – Dipole-Dipole Due to the unequal sharing of electrons, some molecules have a slightly positive and a slightly negative end to them, or a dipole (di-pole = two magnetic poles) These compounds can form weak bonds with one another without combining together completely to create new compounds Ex: Water hydrogen bonds Van Der Waals forces
Isotopes Isotope: An atom that contains a larger or smaller number of neutrons than usual -similar chemical properties -still no charge
Student ntoes
2.1 – Atoms, Ions, and Molecules
Atoms Atom- ______________________________ It would take more than 1 trillion years to count the atoms in a single grain of sand H O
______________ Particles Atoms are made up of 3 smaller parts: 1. _____________(+) – Found in ______________ 2. ____________(0) – Found in _______________ 3. ______________(-) – Energy levels outside of nucleus Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)
____________________ Element- one ____________________________, cannot be broken down If all elements are made up of atoms… what distinguishes between elements?
Reading the periodic table:
Elements in living things “___________________” ____________, ______________, ___________, and ____________make up about 95% of our body Sulfur is needed for proteins Phosphorous is needed for DNA You must memorize these!!!!!
__________________ Compound- a substance made of ____________________________________ ____________________________________ A compound has _______________________than the elements that it is made of What type of chemical compounds have we talked about so far this year? O HH _ ++
Example: Hydrogen and Oxygen are both found as gases naturally on earth BUT… when combined they can form water A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.
Quick review: How are elements different from compounds? Give at least 2 reasons:
Ions form when atoms _____________________________ An _________________is an atom that has gained or lost one or more electrons. _______________ions ________________ions ______________________form between oppositely charged ions. They are held together by electrical force! ______________________________! Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron
Ionic Bond Example:
How do we know if an atom wants to gain or lose electrons? The atom wants _______________________ by moving the ___________amount of electrons So… If it has 3 or less electrons it will give electrons away and become POSITIVELY charged If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged
Atoms share pairs of electrons in covalent bonds. A ________________________ forms when atoms share a pair of electrons. Usually __________________! covalent bonds Oxygen atom (O)Carbon atom (C)Oxygen atom (O) Carbon dioxide (CO 2 ) –multiple covalent bonds –diatomic molecules –Ex: O 2
Molecules __________________- two or more atoms held together by _____________________