The Chemical Context of Life Flashcards
Define an element
An element is a substance which cannot be broken down any further by chemical reactions
Define a compound
A compound is a combination of two or more different elements
What are the 4 essential elements of a living organism?
- CHON
1) carbon
2) hydrogen
3) oxygen
4) nitrogen
What are trace elements?
Substances which are essential to organisms in only minute quantities
Define subatomic particles and identify 3
Subatomic particles are the smallest units of an element. Elements are made up of atoms which are made up of these particles.
1) neutrons
2) electrons
3) protons
What subatomic particles are found in the atomic nucleus?
protons and neutrons are tightly packed within the atomic nucleus
Where are the electrons found in particles?
the electrons of an atom are rapidly moving around the nucleus in orbitals
What is the mass number and the atomic number?
The mass number represents the total number of protons and neutrons found within the atomic nucleus
The atomic number represents the number of protons and the number electrons in a neutral atom
How can one find the number of neutrons in an atom’s atomic nucleus?
Mass number - atomic number = # of neutrons
What are isotopes? Provide an example
Isotopes are different forms of a certain atom in which there is a small difference in the atomic numbers.
ex. carbon-12, carbon-13, carbon-14
What are radioactive isotopes?
Radioactive isotopes are those with an unstable atomic nucleus which spontaneously decay and give off particles and energy.
How are radioactive isotopes used as a tool in medicine?
Radioactive isotopes can be used to track atoms during chemical processes and metabolism in an organism. They can be referred to as radioactive tracers.
What is meant by the potential energy of an electron?
The potential energy of an electron is given by distance from the nucleus. Those that are further from the nucleus have more potential energy whereas those that are closer have less potential energy.
What are valence electrons and a valence shell?
The outermost shell and electrons orbiting the atomic nucleus
What is an orbital?
An orbital is a more accurate idea of where electrons spend 90% of their time while orbiting the nucleus
Describe how electron orbitals may look and their characteristics
- each orbital may only hold up to 2 electrons in each orbital move at different rates
- consist of similar energy levels
- electrons in each
- the first orbital consists of 1 spherical s orbital
- the second orbital consists of 1 larger s orbital and 3 dumbell-shaped p orbital
What does the electronegativity of an atom represent?
The electronegativity of an atom refers to the force of attraction between an atom and electrons
what is the difference between polar and non-polar covalent bonds?
- a nonpolar covalent bond is one in which electrons are shared equally between each element. Each element of the bond consists of similar electronegativities.
- a polar covalent bond is one in which electrons are unevenly shared between elements of the bond as for different electronegativities. This creates partial charges at certain ends of the compound
What are ions and how are they formed?
Ions are atoms with either a negative or positive charge. They are the result of electrons which have been completely stripped away from the pairs from which they were being shared.
What is an ionic bond?
An ionic bond is a pair of ions which are bounded by the attraction of opposite charges.
What is the difference between dry ionic compounds and those submersed in water?
While dry ionic compounds maintain the strength of the bond, when submerged in water, water molecules weaken the force of attraction between the opposite charges acting as a shield between the bonded ions
What are some weak chemical reactions? explain.
- hydrogen bonds : weak non-covalent bonds between partially positive hydrogen and another electronegative atom with an opposite charge
- Vaan der Waals interactions: short-lasting simultaneous bonds formed between atoms of changing partial negative and positive charges. These interactions may only occur in close proximities
ex. london forces, dipole-dipole
How is the molecular shape of an atom determined?
The molecular shape of an atom depends on the position of it’s orbitals
What is a hybrid orbital?
When the valence shell orbital (2s+2p) combines, it forms a 4-tear-dropped shape which extends to all four corners known as a hybrid orbital. This type of orbital is connected to form a geometric shape known as a tetrahedron.
