Chemistry Atomic structure

The half-life of protactinium-226 is 2 minutes. If you started with 20 grams of Pa-226, how many centigrams do you have after 8 minutes?

125 g

Calculate the Average Atomic Mass for Iodine using the following information. mass number 126 percent abundance 17% mass number 127 percent abundance 80% mass number 128 percent abundance 3.0%

126.86 amu

If you had a substance that has a half-life of 12.3 hours and you started with a 200g sample how much of the original material would remain after 36.9 hours?

25.0 g

Tin-126 has a half -life of 100,000 years. How many years does it take to reduce a 100g of 126 to 12.5g?

300,000 years

How many protons, electrons, and neutrons respectively does I-127 have? A. 53,127,74 B. 53,74,53 C. 53,53,127 D. 53,53,74

D. 53,53,74

A beryllium atom has 4 protons, 5 neutrons, and 4 electrons. What is the mass number of this atom? A. 4 B. 5 C. 8 D. 9

D. 9

Which scientist developed the model of the atom shown? A. Chadwick B. Thomson C. Rutherford D. Bohr

D. Bohr

An element's most stable ion of an element X is X+2. If the ion of element X has a mass of 89 36 electrons, what is the identity of the element? A. Zr, 53 neutrons B. Kr, 55 neutrons C. Se, 55 neutrons D. Sr, 51 neutrons

D. Sr, 51 neutrons

What is the correct symbol for an atom with 42 protons and 49 neutrons?

91 Mo 49

A rare isotope of hydrogen, known as tritium, has an atomic of 3 amu. What is the number of protons, neutrons, and electrons respectively for a neutral atom of tritium? A. 1, 2, 1 B. 3, 3, 3 C. 1, 0, 1 D. 2, 1, 2

A. 1, 2, 1

Which model could be described as electrons embedded in a positive jelly-like substance? (plum-pudding model) A. J.J. Thomson's B. Lenard's C. Rutherford's D. Nagaoka's

A. J.J. Thomson's

An atom with 15 protons and 16 neutrons is an atom of A. O B. Ga C. S D. Pd

A. P

The concept of energy levels was proposed by __________________. A. bohr B. dalton C. Rutherford D. j.j. Thompson

A. bohr

The average atomic mass seen on the periodic table is the average of the atomic masses of ________. A. it's naturally occurring isotopes B. two elements to the left C. elements to the left and right D. a red dutchtown bulldog

A. it's naturally occurring isotopes

Which particle determines the identity of an element? A. proton B. electron C. neutron D. alpha

A. proton

How do the mass and size of the nucleus of an atom compare to the mass of an entire atom? A. the masses are similar B. the volumes are similar, but the nucleus has much less mass C. the masses are similar, but the volume of the nucleus is much larger D. the volumes are similar, but the nucleus has much more mass

A. the masses are similar, but the volume of the nucleus is much smaller

Sodium: 12 neutrons, mass number 23 How many electrons are in the atom sodium? A. 22 B. 18 C. 34 D. 35

B. 11

The number of neutrons in one atom of Hg-206 is A. 80 B. 126 C. 206 D. 286

B. 126

Chlorine: 17 protons, 17 electrons, mass number 35 How many neutrons are in the atom of Chlorine? A. 17 B. 18 C. 34 D. 35

B. 18

How many protons and neutrons are in an atom of iron, Fe that has a mass number of 55? A. 26 protons and 55 neutrons B. 26 protons and 29 neutrons C. 29 protons and 26 neutrons D. 26 protons and 26 protons

B. 26 protons and 29 neutrons

Aluminum is an element. Which of the following best describes the smallest particle of aluminum that retains all the properties of aluminum? A. a molecule B. an atom C. a proton D. an electron

B. an atom

Which 2 atoms have the same mass number? Element 1: 8 protons, 10 neutrons, 8 electrons Element 2: 10 protons, 9 neutrons, 10 electrons Element 3: 9 protons, 9 neutrons, 9 electrons Element 4: 8 protons, 11 neutrons, 8 electrons A. atoms 1 & 2 B. atoms 2 & 4 C. atoms 1 & 4 D. atoms 2 & 3

B. atoms 2 & 4

The last of the three subatomic particles to be discovered was the A. proton B. Neutron C. Electron D. Nucleus

B. neutron

11. Which of the following statements are true? i) the number fo protons in am element is the same for all neutral atoms of that element ii) the number of electrons in an element is the same for all neutral atoms of an element iii) the number of neutrons in an element is the same for all neutral atoms of that element A. i, ii, iii are all true B. only i and ii are true C. only ii and iii are true D. only i and iii are true

B. only i and ii are true

Elements are identified according to their number of ____________. A. neutrons B. protons C. electrons D. nucleus

B. protons

A teacher builds a model of a hydrogen atom. A red golf ball is used for a proton, and a green golf ball is used for an electron. Which is not accurate concerning the model? A. number of particles B. relative mass of particles C. types of particles present D. charges of particles present

B. relative mass of particles

Which element has 14 protons? A. nitrogen B. silicon C. aluminum D. sulfur

B. silicon

It would take about _________ electrons to equal the mass of one proton. A. 20 B. 200 C. 2000 D. 20,000

C. 2000

Which of the following is NOT part of Dalton's atomic theory? A. all elements are composed of atoms B. atoms of the same element are identical C. atoms are mostly empty space D. different elements have different atomic masses

C. atoms are mostly empty space

When atoms gain or lose electrons they become A. isotopes B. different elements C. ions D. none of these

C. ions

14 12 c and C are examples of carbon 6 6 A. ions B. neutrons C. isotopes D. valences

C. isotopes

Rutherford's gold foil experiment indicated that A. the nucleus of an atom occupies most of an atom's volume B. positive charges are dispersed throughout the atom C. positive charges are concentrated in a very small core at the center D. protons and neutrons are located in the nucleus

C. positive charges are concentrated in a very small core at the center

4. Which statement would be true about electrons? A. they are negatively charged B. they are located in the space surrounding the nucleus C. they have a relatively low mass D. all the answer choices are true

D. all the answer choices are true

Which two are atoms are isotopes of the same element? Element 1: 8 protons, 10 neutrons, 8 electrons Element 2: 10 protons, 9 neutrons, 10 electrons Element 3: 9 protons, 9 neutrons, 9 electrons Element 4: 8 protons, 11 neutrons, 8 electrons A. atoms 1 & 2 B. atoms 2 & 3 C. atoms 1 & 3 D. atoms 1 & 4

D. atoms 1 & 4

Atoms of the same element having the same atomic number but different mass numbers are called A. isomers B. oribitals C. neutrons D. alpha

D. isotopes

If the atomic mass number of an atom is 35, which statement is most accurate? A. the atom is not an isotope B. the atomic number is less than 17 C. the atom has an even number of neurons in its most common isotope D. the number of protons are not equal the number of neutrons

D. the number of protons are not equal to the number of neutrons

What conclusion did Rutherford make based on the observation that, while bombarding the gold foil, some of the particles bounced back? A. the alpha particles had insufficient mass to pass through the foil B. the alpha particles met a force with a large volume and a positive charge C. the alpha particles met a force with a small volume and a positive charge D. the atom contained electrons that orbited the nucleus like the sun

c. the alpha particles met a force with a small volume and a positive charge