2 Lecture 1 Flashcards
what is the definition of life
growth, reproduction
movement, response to stimuli, metabolism, catabolism, excretion…
what do all living things need to be able to do
things change over time (growth)— if they are alive
ability to reproduce
ability to adapt
ability to use energy to do work and produce heat (homeostasis)
move something, change something, shift the shape of something,
whenever something uses energy it produces heat
what is the cell theory
All living organisms are made of cells
what are cells made of
What is everything made of?
Everything is made of Matter…
Matter is made of elements
Elements are made of atoms
what are atoms made of
Atoms are made up of sub-atomic particles including protons, electrons & neutrons
what are protons
Protons are positively charged & found in the nucleus of an atom
what are electrons
Electrons are negatively charged & orbit the nucleus in energy shells – the number of electrons = the number of protons
what are neutrons
Neutrons have no charge & are found in the nucleus, their number can vary
do protons, electrons and neutrons have mass
Protons and neutrons have mass, but electrons do not have mass
what is matter made of
elements
what are elements
Element = chemically pure substance that cannot be broken down. Elements are made one type of atom
Atoms of each element are characterized how
by a specific number of protons, electrons
what is an atomic number
the number of protons
what is an isotope
Isotopes of the same element have a different number of neutrons
some isotopes are unstable, what does this mean
they are radioactive
what kind of radiation is emitted from some isotopes
α (alpha), β (beta), or γ (gamma) radiation from the atomic nucleus
Life on Earth can be characterized as what
carbon-based
what is the basis of organic molecules
Carbon is the basis of the “organic molecules” that are associated with life
what are the 2 types of molecules
organic and inorganic
what does an organic molecule have to have
has a carbon backbone
at least 1 bond to hydrogen (H)
may also contain oxygen (O) &/or nitrogen (N)
is carbon found in inorganic molecules
yes
what are inorganic molecules
Lack carbon backbone & carbon-hydrogen bonds
to understand chemical bonding, we need to do what
move past the “simple” Bohr model for electrons
what is true for covalent bonds
- A single covalent bond is made of 2 electrons
- The 2 electrons are shared, i.e. one electron comes from each atom
- Atoms can form bonds until their outermost (valence) shell is filled.
1st shell: 2 e 2nd and 3rd shell: 8e
what is the exception for covalent bonds
only exception is: Rare gases (noble gases) are inert— don’t form bonds because the outer (valence) shell is filled (aka they are already stable)
what does it mean by Covalent bonds are very strong,
in that more energy is required to break the bond relative to other types of bonds
A double covalent bond occurs when
atoms share two pairs of electrons
covalent bonds are weak compared to
hydrogen bond
hydrogen bond gives capacity to give very exchangeable but_________________
very strong couplings between molecules
what are ionic bonds
opposite charges
how ling do ionic bonds last for
long lives
what makes ionic bonds so great
ionic binds are long lives, but are part of what makes water such a great environment for life— it acts as a solvent that allows atoms to freely exchange
are hydrogen bonds strong on their own
no, only when there are a lot together
what is van der waals interactions—
can be both attractive and repulsive
what is predictable of covalent bonds
Each covalent bond has a predictable length and angle, which makes it possible to predict the three-dimensional structures of molecules
what are the rules of covalent bonds
- A single covalent bond is made of 2 electrons
- The 2 electrons are shared, i.e. one electron comes from each atom
- Atoms can form bonds until their outermost (valence) shell is filled
Rare gases are inert don’t form bonds because the outer (valence) shell is filled
what are the types of covalent bonds
ionic, hydrogen and just covalent (i think)
are e- always shared equally between covalent bonded atoms
Electrons are not always shared equally between covalently bonded atoms
what is electronegativity
The attractive force that an atom exerts on electrons is called electronegativity
or
the tendency of an atom to attract electrons when it occurs as part of a compound
Ionic bonds form by how
electrical attraction
aka steals e-
which atom attracts the e-
the more electronegative (en) atom attracts electrons
do ionic bonds last long
does not last long… taking something away from something, and as a result the 2 atoms become happier but they are still interacting, so the bond can be easily broken
microscopic interactions are based on what
random collisions
what state can water list in
water can exist as a solid, a liquid or as a gas
as a liquid, the H-bonds between H2O molecules do what
as a liquid, the H-bonds between H2O molecules break continuously but randomly- gives fluidity & surface tension
