Please enable JavaScript.
Coggle requires JavaScript to display documents.
Mindmap of Lego Universe Topic, Screen Shot 2022-02-13 at 2.18.41 PM -…
Mindmap of Lego Universe Topic
Categorizing Matter
compound: a substance made of two or more different elements combined together
mixture: a substance made of two or more elements, compounds, or both
element: substances that cannot be broken down into simpler substances and still have the same properties
separating compounds vs mixtures
substances in a mixture can easily be separated through physical processes because they are not chemically combined together
substances in a compound are chemically bounded, and therefore can only be broken down through chemical processes (NOT physical processes)
atoms: the basic unit of all matter, building blocks of matter
Reactions
Law of Conservation of Mass
the law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed
Chemical Equation
in a chemical reaction, the bonds between atoms in the reactants are broken and new bonds are rearranged and formed to create new compounds
Balancing Equations
the balanced equation should have the same number of each type of atom on both sides of the chemical equation
How to Balance Equations
1) make a list of the number of atoms for each element on BOTH sides of the arrow
2) pick an element that is not equal on both sides (tip: leave separated elements for last)
3) if balancing is required, place the coefficient in front of the substance (will multiply the number of atoms in each compound)
4) check each element again and repeat step 3 with a different substance if necessary
reminder: balancing is for coefficients (BIG numbers), do not change any of the small numbers in a chemical formula
Structure of the Periodic Table
Mendeleev’s Organization of the Periodic Table
In 1869, Mendeleev organized the 65 known elements of the time by their: chemical/physical properties and atomic mass. This was a huge achievement since 27 of the naturally occurring elements haven’t been discovered yet.
Mendeleev arranged elements in rows by increasing atomic mass. Within a row, elements with lower atomic masses were on the left.
Mendeleev started a new row every time the chemical properties of the elements were repeated. Thus, all the elements in a column had similar properties.
periods: horizontal rows (across) the periodic table
groups: vertical columns (down) the table
Periodic Table Trends
atomic number trends: increase in atomic number from left to right of a period
electron shell/atomic radius trends: electron shells/atomic radius increases going down a group
electron trends: elements in the same group have the same number of electrons in their outer/valence shell
Periodic Table Group Characteristics
alkali metals
a group of chemical elements from the s-block of the periodic table with similar properties: silvery appearance and can easily cut with a knife
highly reactive at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1
have many different applications, such as rubidium and caesium atomic clocks, sodium-vapor lamps, and table salt
transition metals
good conductors of heat and electricity
can easily be hammered or bent into a certain shape
usually have a hard and tough exterior
have high melting points
have high densities
less reactive than other periodic groups
halogens
good conductors of heat and electricity
can easily be hammered or bent into a certain shape
usually have a hard and tough exterior
have high melting points
have high densities
less reactive than other periodic groups
noble gases
colorless, odorless, tasteless, and nonflammable gases under standard conditions
widely used in different fields, from incandescent lighting to excimer lasers
Reactivity in the Periodic Table
reactivity trends for alkali metals (group 1): reactivity increases as you go down the group
alkali metals: more likely to lose electrons to achieve a full outermost shell
the outer electron shell grows further from the nucleus going down the group, meaning that the attraction between the nucleus and outer electron gets weaker → an electron can more easily lost
reactivity trends for halogens (group 17): reactivity increases as you go up the group
halogens: more likely to gain electrons to achieve a full outermost shell
atomic radius increases going down a group: electrons are attracted to the nucleus (electrostatic attraction) which means it will more likely gain electrons if there is a shorter distance between the outer shell and the nucleus
Atomic Structure
subatomic particles
proton: positively charged, weighs 1 atomic mass unit, located in the nucleus
electron: negatively charged, weighs 0 atomic mass unit, located in the electron shells
neutron: neutrally charged, weighs 1 atomic mass unit, located in the nucleus
electrostatic attraction: the attraction between particles of opposite charge mostly between protons and electrons
ion: atoms with an electric charge due to the loss or gain of electrons
neutral atoms have the same number of protons and electrons
positive ions have more protons than electrons
negative ions have fewer protons than electrons
isotopes: atoms of the same element with the same number of protons, but a different number of neutrons
isotopes of the same element have the same chemical properties, meaning that they will all react in the same way
the only difference between isotopes are their masses, some isotopes are heavier/lighter than others
atom symbol and names
element symbol: one-letter or two-letter abbreviation for a chemical element name
charge: number of protons - number of electrons
atomic number: number of protons
mass number: number of protons + number of neutrons
Bohr-Rutherford Model: a system consisting of a small, dense nucleus surrounded by orbiting electrons
electron configuration: the distribution of electrons of an atom in molecular orbitals
the first shell can hold up to 2e-, farther shells can hold up to 8e-
energy level: fixed distances from the nucleus of an atom where electrons may be found (lowest energy level: first shell, highest energy level: farthest shell)
