atoms and elements Flashcards
what is an atom
an atom is the smallest unit of matter but still has the properties of an element
what is an atom made of
3 sub-atomic particles called protons, neutrons and electrons
what is the charge of protons, neutrons and electrons
protons +1, neutrons 0, electrons -1
what is the mass of protons, neutrons, electrons
protons 1, neutrons 1, electrons 1/1837
where are protons, neutrons and electrons located
protons and neutrons are in the nucleus and electrons surround the nucleus
what is another unit for atomic mass unit (amu)
dalton
describe the mass of protons and neutrons
they have an identical mass of 1.7x10-24 g
what is the mass of a proton and neutron
1 dalton
what are the two models called
planetary model (bohr model) and electron cloud model schrodinger
when was the planetary model made
1913
when was the electron cloud model made
1926
describe the electron cloud model
represents the two electrons as a cloud of negative charge
describe the planetary model
the electrons are shown as two spheres on a circle around the nucleus
what is mass number
number of protons + number of neutrons
what does a proton determine
an element
what does a neutron determine
an isotope
what is an isotope
a different atomic form of the same element but with different number of neutrons but same number of protons
what is ground state
when the distance between the electron and proton is smaller (than excited state)
what is the excited state
when the distance between the electron and proton is larger (than ground state)
what is the atomic number
sum of protons
what is an element
a substance that can’t be broken down to any other substances by chemical reactions
what is sodium used for
salt, streetlights, in our bodies (for muscles)
what is chlorine used for
toxic gas, water treatment, pvc (plastic)
what is a compound
a substance that consists of two or more different elements combined
what is an example of a compound
water ( 2H2 + O2= 2H2O)
is the atomic number the bottom or top number
top number
is the atomic mass the bottom of top number
bottom number
what is an example of an isotope
carbon= 12C (6 protons), 13C (7 p) and 14C (8 p)
do isotopes behave the same or different in chemical reactions
the same
why are 12C and 13 C (isotopes) more stable than 14C
because the more neutrons you have the more unstable and radioactive the isotope
what happens to the stability and radioactivity of the isotope when the number of neutrons increases
stability decreases and radioactivity increases
what is a radioactive isotope
when a nucleus decays spontaneously which gives off energy and particles
what is radioactive decay
a change in the number of protons
what does radioactive decay cause
causes the atom to transform into an atom of a different element
are atomic masses always whole numbers
no they may be integers
what is the atomic mass of isotopes
the average of the different isotopes
what are the types of radioactive decay
- alpha decay
- beta decay
- gamma decay
what is alpha decay
is when the nucleus loses 2 protons
what is beta decay
when the nucleus either loses or gains a proton
what is gamma decay
when the number of protons doesn’t change so there isn’t a change in element
what can radioactive isotopes be used as in medicine
diagnostic tools
what are radioactive tracers
they are radioactive isotopes that are combined into biologically active molecules which are then used to track atoms during metabolism
what are radioactive tracers also combined with
PET scanners to monitor growth and metabolism of cancers
what happens with energy as we move further away from the nucleus
energy increases
describe the energy of the outer shell
has the highest energy
describe the reactivity of an atom with full shell
unreactive
what is valence
- bonding capacity of an atom
- number of covalent bonds the atom can form (equal to number of unpaired electrons on outer shell)
what is valence electron
an electron in outer shell
what’s valence shell
the outer shell with most energy and with valence electron
what are 3 ways of showing electron configuration
- electron distribution diagram
- superimposed orbitals
- separate electron orbitals
what is chemical behaviour based on
the number of electrons on it’s outer shell
describe the chemical beh of atoms with same number of outer electrons
similar chemical behaviour
what are types of bonds
- covalent bonds
- ionic bonds
- electronegativity
what is a covalent bond
- a shared pair of electrons
- strongest bond
what are examples of covalent bonds
- hydrogen
- oxygen
-water
-methane
what is electronegativity
attraction of an atom to electrons of a covalent bond
what is a non-polar covalent bond
a covalent bond where the two atoms have similar electronegativity
what is a polar covalent bond
a covalent bond between atoms that have different electronegativity
what happens to the electrons in a polar covalent bond
the electrons are pulled closer to the more electronegative atom (delta negative and other delta positive)
what is an ion
an atom that has gained or lost an electron so has gained a charge
what is a cation
a positively charged ion (lost an electron)
what is an anion
a negatively charged ion (gained an electron)
what is an ionic bond
a chemical bond from an attraction between oppositely charged ions
name weak chemical interactions
- hydrogen bonds
- van der walls
what is a hydrogen bond
a weak chemical bond where a partially positive hydrogen atom is attracted to a partially negative hydrogen atom from a different polar bond
when was van der waals discovered
1873
where do van der walls exist
solids, liquids, gases
what are the tree types of van der waals
- dipole induced dipole
- dipole dipole (strongest type)
- london dispersion forces
what is a dipole
a set of separated charges in an atom
what is a dipole dipole
is an attraction between 2 polar molecules
what is a dipole induced dipole
an attraction between a polar molecule and an atom with an induced dipole
what is a london dispersion force
an attraction between a nonpolar atom with an instantaneous dipole and a nonpolar atom with an induced dipole
