Physical and Chemical Changes

Lecture 2.25 21 Physical and chemical changes Physical change is a change that does not change the identity of the substance. Examples include: - Melting Ice - Freezing kool Aid - Tearing paper - Boiling water chemical change is a change that causes the identity of the substance to change. Examples include: Burning wood Digesting food - Potassium reacting with water A chemical change can also be called a chemical reaction. Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form. Physical change object's identity remains the same Cusually involves energy-like heat- and states of matter) Chemical change: object's identity changes (chemical changes happen on a molecular level). Examples: Ethyl alcohol will boil at 78°C Physical Hardness of a diamond → sical Sugar will ferment to form ethyl alcohol comical. - Iron metal melting→ - Iron combining with oxygen to form rust chemical Souring milk chomical .Participation Points WS 1 . a) KBr Potassium Bromide b) Mg504 Magnessium Sulfate C) Ca (NO3)2 : Calcium Nitrate 2. a) Magnesium Phosphate: Mg3(PO4)2 b) carbon tetrachloride: CCla Exam I Study Guide 1-2. Significant figures how many are there? 3-4. Significant figure math 5. Quantitative volume which volume is larger? → I have Il of water and 100ml of water, 6-8. Periodic table Potassium belongs to Alkaline metal 9. Understanding the periodic table If potassium and sodium, why do they put them on the same column? Because they all have similar properties (similar properties to neon). 10. Concept of atoms: 3 subatomic particles of an atom→ protons, neutrons, electrons 11. 2 subatomic particles that share the samelsimilar masses Protons and neutrons 12. Most common element in the human body Oxygen (mass = 15.99) 13. 3 states of matter solid, liqued, gas 14-15. what is the symbol for... Hydrogen, Carbon, Oxygen. 16. Scientists names. Leucippus x Democritus termed the word Atomos. JJ Thompson discovered the electron. 17. What is further out from the atom? Electron 18 what do we mean by octet rule? what does it have to do with electrons? Eight electrons in a valent shell, giving it the same electronic configuration as a noble gas 19-20. Isotope concept Determine the amount/# of protons, neutrons, and electrons in the element 21. What is the difference between a cation and anion? Cations and Anions are both ions. Cations are positive, anions are negative 22. What is the difference between lonic and covalent compounds? lonic compounds: Formed from strong interactions between ions Donates an electron to the other atom. Ionic compounds form between a metal and nonmetal. Covalent compounds: Have bonds where electrons are shared between atoms. (identical atoms). Form between two nonmetals. 23-29. Naming compounds. KBr...ionic/covalent? lonic How would you name that compound. Review polyatomic ions (nitrate, sulfate, phosphate, ammonia) 30. Diatomic compounds/molecules. Cone's with colors) Diatomic molecules are colorful Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, lodine 31. Naming covalent compoundsExample: CBra Carbon tetrabromide 32. When can you use the Roman numerals? With Ionic compounds 33. What is Thompson famous for? Discoved the electron 34. How do you describe an ionic/covalent compound? Extra Questions What subatomic particle is the lightest? Electrons What are 2 elements that are liquids? Mercury (Hg), Bromine (Br) Polyatomic lons: - NH4+ (Ammonia) NO3 (Nitrate) PO43 (Phosphate) CO3 (carbonate) -2 SO42 (sulfate) - May Need To know OH(hydroxide) - C₂H₃O₂ CAcetate) CN-(cyanide) Dmitri Mendeleev: Discovered that the known elements were arranged in order of atomic number Dalton's Atomic Theory: Elements are made of tiny particles called atoms, all atoms of given elements are identical Most abundant elements in the human body Element Mass Percent - Oxygen 65.0 Carbon 18.0 Hydrogen 10.0 Nitrogen 3.0 Calcium 1.4 organic atoms *CHON carbon, hydrogen, oxygen, nitrogen.