Science Quiz Chem Flashcards
The Atom
-Democritus
-matter is made up of particles that cannot be broken down
-He proposed atoms are different sizes, in constant motion, and separated by empty space
Billiard Ball Modle
-John Dalton
-devised an atomic theory that explains the laws behind the behaviour of matter: matter is made up of atoms, each element is made up of its own kind of atom, compounds are the combination of different atoms, and atoms cannot be created or destroyed chemically.
Thompsons experiment-the electron
-JJ Thompson
-discovered very light negative components to the atom
-Suggest the presence of sub atomic particles: atoms contain light negative components embedded in an atom sphere (electrons), the rest of the atomic sphere contains much heavier positive charges (protons), since most items do not have charges, the charges must be equal
The planetary model
-James Chadwick
-found a particle that could penetrate and disintegrate the atom. The neutron.
-Propose that: an atom is an empty sphere with a tiny dense nucleus, nucleus contains protons and neutrons, mass of neutrons, and protons are the same, electrons circle the atom in empty space, neutral atom has an equal number of protons and electrons
Electrons orbit Bohr - Rutherford model
-Neil Bohr
-studied the light it produces when excited by thermal or electrical energy
-Propose the following: electrons orbit, the nucleus, further electrons from the nucleus have greater energy, electrons have a definite energy in their orbit, electrons move from one energy level to another, each orbit holds a certain maximum of electrons (2-8-8)
Mendeleev s grouping
-put the elements in order of increasing atomic mass, but also grouped them according to properties.
-Mendeleev group elements in same group that have similar chemical and physical properties because this will end up having the same number of valence electrons (this affects the reactivity) and will form the same kind of ions.
Mendeleev s predicting new elements and finding missing elements
-when placing the elements in order based on common properties and atomic masses, there were empty spaces, which could predict the properties of unknown elements.
-within 16 years of the periodic table, the missing three elements were discovered (scandium, gallium, and germanium)
How is the period table arranged
-Metals on the left nonmetals on the right metalloids on the staircase
Chemical reactivity
-alkali metals first column: highly reactive with water
-alkali earth metals second column
-Transition metals columns 3-12: not only one characteristic
-halogen’s column 17:extremely reactive compounds-toxic to most organic tissue
-noble gases column 18: does not react with anything
Ions
An atom with an overall positive or negative charge due to an imbalance of protons and electrons
Isotopes
An atom of an element that has the same number of protons but a different number of neutrons (you change the atomic mass, not the atomic number)
Naming ions
-cations are positively charged ions; they have lost electrons; metals
Name= same as the element
Ex. Sodium forms sodium ions.
-anions are negatively charged ions; they have gained electrons; nonmetals
Name= add ‘ide’ to element name
Ex. Oxygen forms oxide ion.
Multivalent
The last shell has different shells (groups 3 to 12)
Mixture
When you put compounds together. They do not bond together. They are just there.
Homogeneous
All looks the same
Heterogeneous
You can see the different parts
Suspension
You can see the different parts, but when you shake or agitate it, the tiny parts become suspended in the area, but if you leave it alone, it will separate on its own
Colloidal dispersion
Physical properties of matter
-Physical state: solid liquid or gas at room temp (25*c)
-Color
-luster: ability to reflect or shininess
-hardness: resistance to being scratched
-ductility: ability to be stretched into wire
-malleability: ability to be hammered into a flat sheet
-Clarity:how clear or how easy it is to see
-crystal form: the shape the crystal forms when it grows
-solubility: can you dissolve it in water
-texture
-Smell
-taste
-viscosity: resistance to flow
-conductivity: how well it conducts electricity
-Melting/boiling point
-toxicity: will it kill you and how?
-density: mass/volume (how much matter and how much space)
-brittleness-how easy it shatters when hit
Chemical properties of matter
occurs when a substance changes into a new substance:
-combines with oxygen
-Interacts with an acid
-combustion, flammability
-Reacts with light
Possible indicators of a chemical change
-a new colour appears
-heat and or light is given off
-bubble bubbles are made or gas (smell) is given off
-a solid precipitate form from two liquids
-the change is difficult to reverse
Polyatomic ions
Group of ions. Has an overall ionic charge.
More that two elements have been combined and one has to be a metal
Names of polyatomic ions
-begins with per (No4 add 1 O)
-end in ate (No3)
- end in ite (No2 take away 1 O)
-begins with Hypo ( No take away 2 O)
Atomic Radius
-radius increased as you go left and down
-as you go down it’s a whole ring
