Chemistry (H) Midterm

How do you calculate kelvin from Celsius

C+273.15

How do you calculate Celsius from kelvin

K-273.15

What digits count as sig figs?

Sandwich zeros, trailing decimal zeros, non zero digits

What digits do not count for sig figs

trailing zeros, leading zeros

What are the sig fig rules for adding and subtracting

use the least decimal places in answer

What are the sig fig rules for multiplication

use the least significant figures in answer

What is the formula for percent error

(|experimental value-accepted value|/accepted value) x 100

Define Physical properties

Characteristics which do not change the substances chemical identity and can be observed

Example of physical properties

color, density, melting point etc.

Define Chemical properties

how a substance behaves in a chemical reaction

Examples of chemical properties

flammability, oxidation, acidity etc.

Define Physical change

a change that effects the form of substance, not chemical composition

examples and descriptive words of physical changes

melting, freezing, crumpling, cutting

are physical changes reversible

yes

define chemical change

one substance's combination with another form to create a new substance

example and descriptive words of chemical change

rust, burning, cooking, combustion etc.

Are chemical changes reversible?

no

Shape of solids

rigid

Shape of liquid

takes shape of container

shape of gas

takes shape of container

volume of solid

fixed

volume of liquid

fixed

volume of gas

determined by container

Solids compressibility

difficult

liquid compressibility

difficult

gas compressibility

easy

Define Homogeneous mixtures

uniform throughout the entire mixture

Define heterogeneous mixture

composition varies throughout mixture

example of homogeneous mixture

milk, sea water, air

example of heterogeneous mixture

caeser salad, chicken noodle soup, cereal in milk

How are mixtures and compounds different

Mixtures are physical combination of substances with individual properties while a compound is a chemical combination of elements that can only be separated by chemical reaction

define an atom

the smallest part of an element that still retains the property

What is a protons charge, mass, and location

Positive charge, 1 atomic mass unit, nucleus

What is a electrons charge, mass, and location

negative charge, 0 atomic mass units, outside nucleus

What is a neutron charge, mass, and location

neutral, 1 atomic mass unit, nucleus

How do acids taste

sour or tart

How do acids feel

sharp stings

how do acids react with metal

vigorous and produce gas

how do acids react with red litmus

no change

how do acids react with blue litmus

turns red

pH range of acids

0-7

examples of acids

lemon juice, vinegar

How do bases taste

bitter

how do bases feel

smooth, slippery

how do bases react with metals

no reaction

how do bases react with red litmus paper

turns blue

how do bases react to blue litmus

no change

pH range of bases

7-14

example of bases

bleach, baking soda, soapy water

Heat

The energy transferred between objects that are at different temperatures

System

A group of parts that work together as a whole

surroundings

everything outside the system

specific heat capacity

the energy required to raise the temperature of one gram of a substance by one degree Celsius

thermodynamically favored

A reaction that will occur on its own given enough activation energy

law of conservation of energy

Energy cannot be created or destroyed

entropy

A measure of disorder or randomness.

Enthalpy

total energy of a system

Exothermic traits

negative change in H, releases heat, hot to cold, gas to liquid to solid, particles slow, example is a hand warmer

Endothermic traits

+ change in H, absorbs heat, cold to hot, solid to liquid to gas, particles speed up, example is ice melting

what does the quantum mechanical model state?

electrons do not travel in defined orbits, they are localized in orbitals

What was bohr's model and what were it's limitations?

A model of hydrogen, which had limitations because it only applied to one element and that electrons do not travel in orbits

What two states can electrons be found in?

Ground and excited states

How many energy levels are there?

7

How many electrons can each orbital hold

2

Aufbau's principle

electrons occupy the orbitals of lowest energy first

Hund's law

Electrons will fill empty orbitals before pairing up with opposite spins

Pauli exclusion principle

each electron must have opposite spins to pair in an orbital

How do the electrons in an orbital spin

opposite directions

what shape are s orbitals

spheres

what shape are p orbitals

dumbbell

Who came up with the first periodic table

Mendeleev

Who is credited with the current model of the periodic table and how was it organized

Henry Mosely, who organized it by increasing atomic number (proton count).

The rows of the period table are called _____?

periods

The columns of the period table are called _____?

groups

Group 1's name, valence electrons, reactivity are?

Alkali metals, 1, reactive

Group 2's name, valence electrons, reactivity are?

alkaline earth metals, 2, reactive

Group 3-12's name, valence electrons are?

Transition metals, 2

Group 17's name, valence electrons, reactivity are?

Halogens, 7, reactive

Group 18's name, valence electrons, reactivity are?

noble gases, 8, stable

What are metal's location on the periodic table?

left of staircase

What are non-metal's location on the periodic table?

right of staircase

What are metalloids location on the periodic table?

they are the staircase

Metal's properties

ductile, malleable, luster, good conductor of heat and electricity, solid at room temperature

Metalloid's properties

shares properties of metals and non metals, semi-conductor

Non-metals properties

Not ductile, not malleable, not luster, poor conductors, form varies at room temperature

What are the 4 sublevels on a periodic table

S,P,D,F

What two sublevels hold valence electrons

S and P

Octet rule

atoms lose or gain electrons to get eight valence electrons

Ionization energy

The amount of energy required to remove an electron from an atom

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons

Where is the staircase of metalloids?

B to Po

Which way does atomic radius trend?

Left and Down

Which way does electronegativity trend?

Right and Up

Which way does ionization trend?

Right and Up

Which way do metallic characteristics trend?

Left and down

What happens to ionization energy when more electrons are removed and why?

It increases because it takes more energy to remove more electrons

Definition of ionic bond

the electrostatic attraction where electrons are transferred from metals (cations) and non metals (anions)

Properties of ionic compounds

Brittle, high melting points, generally dissolve in water, good conductor of electricity when molten or aqueous

Lattice energy

the energy required to separate 1 mole of ions in an ionic compound

What is the 'sea' of electrons model?

Metals contribute valence electrons to a sea of electrons which move easily allowing the conduction of heat and electricity.