Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
48 Cards in this Set
- Front
- Back
What is matter composed of? |
Elements |
|
What is an element? |
Any substance that cannot be broken down into another substance, at least by any normal chemical reaction |
|
How many naturally occurring elements do we have? |
92 - others have been created or synthesized by scientists |
|
How many elements are considered essential for life and how many of them make up 96% of our body mass? |
25 elements, 4: carbon, nitrogen, oxygen, and hydrogen |
|
Smallest units of matter? |
Atoms |
|
What are atoms composed of? |
Subatomic particles: electrons, protons, and neutrons |
|
What are protons? |
subatomic particles found in the nucleus of the atom. Have a positive charge and an atomic mass of 1 |
|
What are neutrons? |
Subatomic particles found in the nucleus of the atom. Have an atomic mass of 1, but neutrons don't have positive or negative charge so they are neutral |
|
What are electrons? |
Subatomic particles that are NOT found in the nucleus. Found way far away from the nucleus and orbiting/circling the nucleus. Electrons have a negative charge |
|
What is Atomic Mass? |
Equal to the number of protons plus the number of neutrons in the atom |
|
What is Atomic Number? |
The number of protons in an atom |
|
What determines the identity of an element? |
Atomic Number |
|
What are isotopes? |
Atoms of an element that have a different number of neutrons so they have different atomic masses but same atomic number |
|
What are unstable isotopes called? |
Radioactive isotopes. When they decay the energy they give off is radiation |
|
3 ways of representing atoms |
1.The shell model 2. The ball model 3. The electron density cloud model |
|
How do the electrons of an atom fill the shells? |
The innermost shell (1st shell), then the 2nd shell is filled, then 3rd etc |
|
How many electrons can each shell hold? |
1st electron shell holds 2, the 2nd shell holds eight |
|
What is valence shell? |
The outermost shell of an atom, holds valence electrons |
|
What happens if the valence shell is not full? |
It is considered unstable and will interact with the valence electrons of other atoms so that it can fill the outermost shell |
|
How is a molecule created? |
When 2 or more atoms bond together |
|
What is a compound? |
Molecules that contain atoms of more than one element in proportions that do not vary |
|
2 Primary Types of Chemical Bonds |
Ionic Bonds and Covalent Bonds |
|
What is an ion? |
An atom of molecule that has a net electric charge |
|
What is an Ion with a positive charge? |
Cation : if an atom loses electrons, it is left with a net positive charge (because it has more protons than electrons) |
|
What is an ion with a negative charge? |
Anion : if an atom gains electrons, it develops a net negative charge |
|
What's an ionic bond? |
Electrical attraction between cation and anion |
|
How are covalent bonds formed? |
When atoms share electrons in their valence shells |
|
What is a single covalent bond? |
If atoms share a single pair of electrons |
|
What is a double covalent bond? |
If atoms have to share 2 pairs of electrons in order to fill the valence shell |
|
Non-polar covalent bonds |
Are created when atoms share the electrons equally |
|
Polar covalent bonds |
Are created when there is unequal sharing of electrons |
|
When are polar covalent bonds created? |
When one of the atoms has a stronger pull on the electron, compared to the other atom |
|
Electronegative |
The atom with the stronger pull (electronegativity of an atom is the tendency to attract electrons) |
|
What do polar covalent bonds lead to the creation of? |
Polar Molecules |
|
What are polar molecules? |
A molecule that will have one region that has a slight negative charge and one region that has a slight positive charge (so it has two 'poles') |
|
Which is the most important polar molecule in our body? |
H20 (Oxygen has the stronger pull on the electron so it is an electronegative atom) |
|
What is a hydrogen bond? |
The attraction between a slight positive charge on the hydrogen atom of one polar molecule and a slight negative charge of an oxygen or nitrogen of another polar molecule |
|
What happens during chemical reactions? |
Chemical bonds are formed or broken |
|
What is the formula for chemical reaction? |
Reactants + Reaction = Products (resulting molecule that is produced) |
|
What does catabolism refer to? |
The decomposition reactions that occurs within a cell |
|
Decomposition Reaction |
When large, complex molecules are broken down in the body, a molecule of water is absorbed during the process |
|
Hydrolysis |
Water molecule that is necessary for the breakdown to occur |
|
What does anabolism refer to? |
The synthesis of new molecules in the body |
|
Synthesis Reaction |
when smaller molecules are used to create larger moleucles |
|
Dehydration synthesis |
a complex molecule is formed by the removal of water (opposite of hydrolysis) |
|
What is reversible reactions? |
Chemical reactions that can occur in both directions - synthesizing or decomposing |
|
What is activation energy? |
The amount of energy that is necessary to start a chemical reaction |
|
What do enzymes do? |
They speed up chemical reactions by lowering the activation energy. Act as catalysts for chemical reactions |