Chemistry Vocabulary Flashcards
Valance Electrons
Electrons found in the outermost orbit of an atom (found in valence shell).
When is an atom neutral?
When the number of electrons is equal to the number of protons.
When is an atom charged?
When the number of electrons is not equal to the number of protons.
Ion
An ion is a charged atom, formed when electrons are either gained or lost. Valence electrons are always the first to be lost.
Hardness
A measure of the resistance of a solid to being scratched. Ex. a diamond is hard, chalk is soft.
State
At room temperature the state at which the substance occurs (either solid, liquid, or gas) Ex. water-liquid, gold-solid, helium-gas.
Malleability
A measure of how easily the substance can be bent or hammered into a certain. Applies to solid metals. Ex. malleable- gold (at 24k), not malleable-steel.
Ductility
A measure of how easily a metal can be pulled to form wires. Ex. ductile-copper, aluminum, not ductile- calcium, lithium.
Crystal Form
If a substance is made of crystals, then it will have a unique crystal pattern or form. Ex. snow, sugar, salt, carbon.
Solubility
A measure of how easily a substance dissolves in water. Ex. Sugar, salt, vinegar, dissolve in water, oil does not.
Viscosity
A measure of thick a liquid is when pouring it. Ex. High viscosity- ketchup, maple syrup, molasses, low viscosity- water, olive oil, vinegar.
Combustibility
A measure of how easily a substance catches on fire or explodes. Ex. Hydrogen is combustible, helium is not.
Reaction with acid
Whether a substance reacts with acid how it reacts if it does. Ex. baking soda, reacts with acid and forms carbon dioxide and water.
Physical Property
A physical property is an aspect of a substance that does not involve forming any new substances. They can be experienced through senses.
What is something each substance has that is unique?
Each substance has a unique melting point and boiling point.
What can be used to identify a mystery substance?
Melting, boiling point and density.
What can affect melting and boiling points?
The purity of a substance can affect the melting and boiling points.
State the temperatures water melts/freezes and boils at?
Water melts/freezes at 0 degrees celsius and boils at 100 degrees celsius.
Density
A measure of how much matter (mass) is present per unit of volume. It indicates how tightly the particles are packed.
Give an example of density.
The density of water is 1g/mL. Ice floats so it is less dense than that, metals sink so they are more dense.
Physical Change
A physical change is a change that does not create any new substances. They may include changes of state. They are reversible.
Chemical Change
A chemical change is a change in a substance that produces new substances. These are reversible. (If the product of the starting substances is different then there has been a chemical change.)
Chemical Property
How a substance predictably behaves around other substances. Some are very reactive, some are not. Some react under only certain conditions.
What is special about how the periodic table is organized?
The periodic table is organized in such a way that reactions can be predicted based on the chemical properties of elements.
Oxidation number
The oxidation number of an element tells you how far an element is away from a full valence shell. It can be positive or negative. Ex. Aluminum has an oxidation of 3+.
Polyatomic ion
An ion that has a stable group of several atoms acting together as a charge particle.
How is charge shared throughout a polyatomic ion?
The charge in this type of ion is shared over the whole ion, unlike just one atom.
What is an example of a polyatomic ion? Describe it?
Sodium Phosphate, is a white solid, quite stable and an electrolyte. The chemical formula for sodium phosphate is: Na3PO4
Molecular Compounds
Molecular compounds are pure substances formed from two or more non-metals.
