Unit 1-3 Flashcards
What is a mixture?
In chemistry, a mixture is a material made up of two or more different substances which are physically combined. A mixture is the physical combination of two or more substances in which the identities are retained.
What is a homogeneous mixture?
Homogeneous mixtures have the same composition throughout, and the individual parts of the mixture are not easily identifiable. While we normally think of solutions as liquids, such as soft drinks and lemonade, they can actually be in the form of solids, liquids, and gases. Homogeneous mixtures can also be a combination of these forms, as in a liquid-gas mixture.
What is a heterogeneous mixture?
In a heterogeneous mixture, the substances do not blend smoothly throughout, and the individual substances that compose the mixture can be detected. Heterogeneous mixtures can typically be separated back into their individual components through chemical or physical means.
What is a pure substance?
A pure substance or chemical substance is a material that has a constant composition (is homogeneous) and has consistent properties throughout the sample. A pure substance participates in a chemical reaction to form predictable products. In chemistry, a pure substance consists only of one type of atom, molecule, or compound.
What is an impure substance?
Impure substances may be mixtures of elements, mixtures of compounds, or mixtures of elements and compounds.
What is a compound?
Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements.
Ex. Methane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound.
What is an element?
A chemical element is a species of atom having the same number of protons in their atomic nuclei. For example, the atomic number of oxygen is 8, so the element oxygen describes all atoms which have 8 protons.
What is matter?
Anything that has mass and takes up volume.
What is mass? What is it not?
A measure of the total quantity of matter in an object. IT IS NOT WEIGHT
What is volume?
A measure of the total space occupied by an object.
What is density?
A ratio of the mass of an object to the volume occupied by that object.
Density= mass/volume
- if the mass increases, so does the density* = proportional relationship (up and up)
- if the volume decreases, the density gets larger* = inverse relationship (up and down)
What are the two types of observations?
Quantitative: involving measurement that can be written down with numbers (ex. Hairs on your head)
Qualitative: not involving measurement (ex. Hair color)
Density = X/X
Mass/ Volume
Density usually _____ with increasing temperatures.
Decreases
Density is _____ proportional to mass.
Directly
Density is _____ proportional to volume.
Inversely
Can an element be broken down into simpler substances in any way?
No
What is an atom?
It is the smallest particle that can exist and still have the properties of the element.
What is a subatomic particle?
A very small particle that is the building block for atoms. It consists of protons, electrons, or neutrons.
Proton Charge:
+1
Electron charge:
-1
Neutron charge:
0
What do subatomic particles consist of?
Protons, electrons, and neutrons.
Relative mass of an electron:
Relative- 1
Relative mass of a proton:
Relative- 1837
Relative mass of a neutron.
Relative- 1839
Atomic number definition and symbol
(Z) - number of protons in the nucleus of an atom
Mass number definition and symbol
(A) - number of protons (Z) plus the number of neutrons
Atoms of the same element have the same number of _____, but can have different numbers of _____ and _____.
Protons - Neutrons and Electrons
How is an atom neutral?
It has the same number of protons and electrons.
Atoms of the same element that have the same number of protons and electrons but different numbers of neutrons are called:
Isotopes
What is a valence electron?
The amount of electrons in the outermost shell.
Non metals always form _____
Anions
Metals will always form _____
Cations
What is a polyatomic ion?
A cation or an anion that contains more than one element.
Ionic compounds are between _____ and _____
Metal and nonmetal (cation and anion)
Covalent compounds are between _____ and _____
Nonmetal and nonmetal (can include metalloids)
Cations are
Positive
Anions are
Negative
What is a molecule?
a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
What defines a halogen?
Reactive, nonmetallic elements that form strongly acidic compounds with hydrogen from which simple salts can be made.
What defines a noble gas?
A gaseous element believed to be totally unreactive and the most stable of all the elements
List characteristics of alkaline earth metals:
Shiny, silvery white, hard, reactive at standard temp and pressure, low density, low melting and boiling point (higher than alkali metals though)
List the characteristics of alkali metals:
Soft (can be cut with a knife), low density, low melting and boiling points, good conductors of heat and electricity, shiny.
Valence electrons determine ____________.
The chemical properties of an element
Valence electrons are the electrons involved in _____!
Bonding!
