Chemisty midterm exam

Which of the following is not a physical change?

Burning

Which of the following is not a chemical change

Melting

A physical change occurs when

A leaf changes color in the fall

A physical change occurs when

Glue gun melts on a glue stick

The number of grams qual to 0.5 kg is

500.

A measurment that closely agrees with the accepted value is best described as

Accutate

The measuremeant 0.035550g rounded off to two significant figures would be

0.036

The number of significant figures in the measurment 0.000305 kg is

3

The number of significant figures in the measurement 2010 cm is

3

How is the measurement 0.000065 cm written in sientific notation

6.5 × 10 -5

The avarage distance between earth and the moon is 386000km. Expressed in scientific notation, this distance is written as

3.86 × 10 5

Because a few positively charged particles bounced back from the foil, Ruthford concluded that such particles were

Repelled densly by packed regions of positive charge

A positievly charged particle with the mass 1.673 × 10 -24 g is a

Proton

A nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a

Neutron

The nucleus of an atom has all of the following characteristics except

Contains nearly all of the atoms volume

Which part of an atom has a mass approcimately equal to 1/2000 of the mass of a proton

Electron

The nucleus of most atom sis composed of

Tightly packed protons and neutrons

Protons within a nucleus are attracted to each other by

Nuclear forces

An atom is electrically neutral because

The numbers of protons and electrons are neutral

The smallest unit of an element that can exist either alone or in combintation with other such particles of the same or different elements is the

Atom

Isotopes of an element contain different numbers of

Neutrons

The atomic number of oxygen, 8, indicates that there are eight

Protoons in the nucleus of an oxygen atom

An atom of potassium has 19 protons and 20 neutrons. what is its mass number

39

Discovered electrons

Thomson

Discovered neutrons

Chadwick

Concluded nucleus was dense and positive

Rutherford

First to use the term atom

Democritus

The distance between two successive peaks on adjacent waves is its

Wavelength

The emission of electrons from metals that have absorbed photons is called the

Photoelectric effect

For an electron in an atom to change from ground state to an excited state

Energy must be absorbed

According to the Bhor modle of the atom, the single electron of a hydrogen atom circles the nucleus

IN specific, allowed orbitals

How many quantum numbers are needed to describe the energy state of an electron in an atom

4

The main energy levels of an atom are indicated by the

Principle quantum numbers

The spin guantum number of an electron can be thoguht of as describing

The direction of electron spin

The statement that an electron occupies the lowest available energy orbital is

The Aufbau principle

The statement that no two electrons in the same atom can have the same four quantum numbers is

The pauli exclusion principle

The element with the electron configuration

As

The element that is shown with the following noble gas notation

Pb

Mendeleev noticed that properties of elements usally repeated at regular intervals when the elements were arranged in order of inceasing

Atomic mass

What are the elements with atomic numbers from 58 to 71 in the periodic table called

The lanthanide elements

Argon, krypton, and xenon are

Noble gases