topic two Flashcards
Chemistry
What is a physical change?
Any change not involving the substances chemical identity Ex- ice melting
What is a chemical change?
When 2+ chemicals react to form different properties
What is a pure substance?
Consists of only of kind of matter. Elements and compounds are pure substances
What is a mechanical mixture?
A mixture in which you can see the different substances Ex- soup
What is a solution?
The substances are not visibly distinct Ex- kool aid
Suspension vs colloid
Suspension- tiny particles of one substance are held within another cloudy mixture. These particles can be filtered out Ex- tomato juice
Colloid- Cloudy mixture but particles can NOT be filtered out Ex- milk
Evidence of a chemical change
-change in colour
-change in odour
-Formation of a solid
-Formation of a gas
-Release or absorption of heat
Daltons billard ball
Matter is made up of solid spheres called atoms
Thomsons raisin bun
electrons are in bedded in the atom
Rutherford
The nucleus is composed of protons
bohr
electrons exist in orbitals
Quantum mechanics theory
electrons exist in a charged cloud around the nucleus
Who created the periodic table?
Dmitri Mandeleev
What is a period?
Horizontal row on the periodic table
What is a group/family?
Vertical row on the periodic table. The same group have similar properties. Group 1= alkali metals Group 2= alkaline-earth metals Group 17= halogens Group 18= noble gases
Atomic number
number of protons in the nucleus of the atom. Number of protons= number of electrons
Atomic mass
total mass of the protons and neutrons in the nucleus
What do you calculate the mass number?
number of protons + number of neutrons= mass number
mass number - atomic number = number of neutrons
In the formula H20 how many particles of each substance do you have?
Hydrogen- 2
Oxygen- 1
What is an ionic compound?
A ionic compound is a pure substance formed by attraction between particles of opposite charge called ions. They transfer electrons. Properties include- high melting point/ boiling point, conductor, crystal shape, solid at room temperature
Cations vs anions
Cations- positive ions with lost electrons, metals tend to form cations
anions- Gained electrons, usually non-metals
How do you name an ionic compound?
use the full name of the metal first, put the non-metal last and change the ending to ide (if polyatomic ion do NOT change to ide), if the cation has more than one possible charge specify which charge in roman numerals (balance the charges when writing formula)
What is a molecular compound?
When non-metals combine. Properties include- low melting/boiling points, insulators, solid/liquid/or gas at room temperature
How do you name a molecular compound?
use the full name of the first element, put the last element and change ending to ide, use correct prefix on each (note- if the first one only has one atom no prefix is needed)
What is a reactant vs a product?
Reactants are the materials that come together to form a reaction
The product is the new material produced from the reaction
How do you write a chemical equation?
Reactants on the left products on the right:
wood+oxygen=carbon dioxide+energy+water
what is exothermic?
Reactions that release energy (get hot, fire)
what is endothermic?
when is absorbs heat energy (get cold)
what is corrosion?
Also known as oxidizing, it means rusting. (when oxygen in the air reacts with a metal)
What is cellular respiration?
It is the reaction of oxygen and glucose from food to produce water, carbon dioxide and energy.
what is the law of conservation of mass?
If a closed container, the original weight of the substances will weigh the same after. Ex- mixing 2 chemicals in a closed beaker, the weight will be the same throughout
what is a catalyst?
Speeds up the reaction rate, without changing the experiment. It is NOT a reactant.
What helps speed up a reaction?
Concentration- more reactants more quickly
Temperature- increase in temperature increases reaction rate
Surface area- When there is more surface area the reaction will happen faster
